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OBD-II PIDs

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OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool.

SAE standard J1979 defines many OBD-II PIDs. All on-road vehicles and trucks sold in North America are required to support a subset of these codes, primarily for state mandated emissions inspections. Manufacturers also define additional PIDs specific to their vehicles. Though not mandated, many motorcycles also support OBD-II PIDs.

In 1996, light duty vehicles (less than 8,500 lb or 3,900 kg) were the first to be mandated followed by medium duty vehicles (8,500–14,000 lb or 3,900–6,400 kg) in 2005.[1] They are both required to be accessed through a standardized data link connector defined by SAE J1962.

Heavy duty vehicles (greater than 14,000 lb or 6,400 kg) made after 2010,[1] for sale in the US are allowed to support OBD-II diagnostics through SAE standard J1939-13 (a round diagnostic connector) according to CARB in title 13 CCR 1971.1. Some heavy duty trucks in North America use the SAE J1962 OBD-II diagnostic connector that is common with passenger cars, notably Mack and Volvo Trucks, however they use 29 bit CAN identifiers (unlike 11 bit headers used by passenger cars).

Services / Modes

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There are 10 diagnostic services described in the latest OBD-II standard SAE J1979. Before 2002, J1979 referred to these services as "modes". They are as follows:

Service / Mode (hex) Description
01 Show current data
02 Show freeze frame data
03 Show stored Diagnostic Trouble Codes
04 Clear Diagnostic Trouble Codes and stored values
05 Test results, oxygen sensor monitoring (non CAN only)
06 Test results, other component/system monitoring (Test results, oxygen sensor monitoring for CAN only)
07 Show pending Diagnostic Trouble Codes (detected during current or last driving cycle)
08 Control operation of on-board component/system
09 Request vehicle information
0A Permanent Diagnostic Trouble Codes (DTCs) (Cleared DTCs)

Vehicle manufacturers are not required to support all services. Each manufacturer may define additional services above #9 (e.g.: service 22 as defined by SAE J2190 for Ford/GM, service 21 for Toyota) for other information e.g. the voltage of the traction battery in a hybrid electric vehicle (HEV).[2]

The nonOBD UDS services start at 0x10 to avoid overlap of ID-range.

Standard PIDs

[edit]

The table below shows the standard OBD-II PIDs as defined by SAE J1979. The expected response for each PID is given, along with information on how to translate the response into meaningful data. Again, not all vehicles will support all PIDs and there can be manufacturer-defined custom PIDs that are not defined in the OBD-II standard.

Note that services 01 and 02 are basically identical, except that service 01 provides current information, whereas service 02 provides a snapshot of the same data taken at the point when the last diagnostic trouble code was set. The exceptions are PID 01, which is only available in service 01, and PID 02, which is only available in service 02. If service 02 PID 02 returns zero, then there is no snapshot and all other service 02 data is meaningless.

When using Bit-Encoded-Notation, quantities like C4 means bit 4 from data byte C. Each bit is numbered from 0 to 7, so 7 is the most significant bit and 0 is the least significant bit (See below).

A B C D
A7 A6 A5 A4 A3 A2 A1 A0 B7 B6 B5 B4 B3 B2 B1 B0 C7 C6 C5 C4 C3 C2 C1 C0 D7 D6 D5 D4 D3 D2 D1 D0

Service 01 - Show current data

[edit]
PIDs
(hex)
PID
(Dec)
Data bytes returned Description Min value Max value Units Formula[a]
00 0 4 PIDs supported [$01 - $20] Bit encoded [A7..D0] == [PID $01..PID $20] See below
01 1 4 Monitor status since DTCs cleared. (Includes malfunction indicator lamp (MIL), status and number of DTCs, components tests, DTC readiness checks) Bit encoded. See below
02 2 2 DTC that caused freeze frame to be stored. Decoded as in service 3
03 3 2 Fuel system status Bit encoded. See below
04 4 1 Calculated engine load 0 100 % (or )
05 5 1 Engine coolant temperature -40 215 °C
06 6 1 Short term fuel trim (STFT)—Bank 1 -100 (Reduce Fuel: Too Rich) 99.2 (Add Fuel: Too Lean) % (or )
07 7 1 Long term fuel trim (LTFT)—Bank 1
08 8 1 Short term fuel trim (STFT)—Bank 2
09 9 1 Long term fuel trim (LTFT)—Bank 2
0A 10 1 Fuel pressure (gauge pressure) 0 765 kPa
0B 11 1 Intake manifold absolute pressure 0 255 kPa
0C 12 2 Engine speed 0 16,383.75 rpm
0D 13 1 Vehicle speed 0 255 km/h
0E 14 1 Timing advance -64 63.5 ° before TDC
0F 15 1 Intake air temperature -40 215 °C
10 16 2 Mass air flow sensor (MAF) air flow rate 0 655.35 g/s
11 17 1 Throttle position 0 100 %
12 18 1 Commanded secondary air status Bit encoded. See below
13 19 1 Oxygen sensors present (in 2 banks) [A0..A3] == Bank 1, Sensors 1-4. [A4..A7] == Bank 2...
14 20 2 Oxygen Sensor 1
A: Voltage
B: Short term fuel trim
0
-100
1.275
99.2
V

%

(if B==$FF, sensor is not used in trim calculation)
15 21 2 Oxygen Sensor 2
A: Voltage
B: Short term fuel trim
16 22 2 Oxygen Sensor 3
A: Voltage
B: Short term fuel trim
17 23 2 Oxygen Sensor 4
A: Voltage
B: Short term fuel trim
18 24 2 Oxygen Sensor 5
A: Voltage
B: Short term fuel trim
19 25 2 Oxygen Sensor 6
A: Voltage
B: Short term fuel trim
1A 26 2 Oxygen Sensor 7
A: Voltage
B: Short term fuel trim
1B 27 2 Oxygen Sensor 8
A: Voltage
B: Short term fuel trim
1C 28 1 OBD standards this vehicle conforms to 1 250 enumerated. See below
1D 29 1 Oxygen sensors present (in 4 banks) Similar to PID $13, but [A0..A7] == [B1S1, B1S2, B2S1, B2S2, B3S1, B3S2, B4S1, B4S2]
1E 30 1 Auxiliary input status A0 == Power Take Off (PTO) status (1 == active)
[A1..A7] not used
1F 31 2 Run time since engine start 0 65,535 s
20 32 4 PIDs supported [$21 - $40] Bit encoded [A7..D0] == [PID $21..PID $40] See below
21 33 2 Distance traveled with malfunction indicator lamp (MIL) on 0 65,535 km
22 34 2 Fuel Rail Pressure (relative to manifold vacuum) 0 5177.265 kPa
23 35 2 Fuel Rail Gauge Pressure (diesel, or gasoline direct injection) 0 655,350 kPa
24 36 4 Oxygen Sensor 1
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
0
0
< 2
< 8
ratio
V
25 37 4 Oxygen Sensor 2
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
26 38 4 Oxygen Sensor 3
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
27 39 4 Oxygen Sensor 4
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
28 40 4 Oxygen Sensor 5
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
29 41 4 Oxygen Sensor 6
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
2A 42 4 Oxygen Sensor 7
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
2B 43 4 Oxygen Sensor 8
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Voltage
2C 44 1 Commanded EGR 0 100 %
2D 45 1 EGR Error -100 99.2 %
2E 46 1 Commanded evaporative purge 0 100 %
2F 47 1 Fuel Tank Level Input 0 100 %
30 48 1 Warm-ups since codes cleared 0 255
31 49 2 Distance traveled since codes cleared 0 65,535 km
32 50 2 Evap. System Vapor Pressure -8,192 8191.75 Pa

(AB is two's complement signed)[3]

33 51 1 Absolute Barometric Pressure 0 255 kPa
34 52 4 Oxygen Sensor 1
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
0
-128
< 2
<128
ratio
mA
35 53 4 Oxygen Sensor 2
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
36 54 4 Oxygen Sensor 3
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
37 55 4 Oxygen Sensor 4
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
38 56 4 Oxygen Sensor 5
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
39 57 4 Oxygen Sensor 6
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
3A 58 4 Oxygen Sensor 7
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
3B 59 4 Oxygen Sensor 8
AB: Air-Fuel Equivalence Ratio (lambda,λ)
CD: Current
3C 60 2 Catalyst Temperature: Bank 1, Sensor 1 -40 6,513.5 °C
3D 61 2 Catalyst Temperature: Bank 2, Sensor 1
3E 62 2 Catalyst Temperature: Bank 1, Sensor 2
3F 63 2 Catalyst Temperature: Bank 2, Sensor 2
40 64 4 PIDs supported [$41 - $60] Bit encoded [A7..D0] == [PID $41..PID $60] See below
41 65 4 Monitor status this drive cycle Bit encoded. See below
42 66 2 Control module voltage 0 65.535 V
43 67 2 Absolute load value 0 25,700 %
44 68 2 Commanded Air-Fuel Equivalence Ratio (lambda,λ) 0 < 2 ratio
45 69 1 Relative throttle position 0 100 %
46 70 1 Ambient air temperature -40 215 °C
47 71 1 Absolute throttle position B 0 100 %
48 72 1 Absolute throttle position C
49 73 1 Accelerator pedal position D
4A 74 1 Accelerator pedal position E
4B 75 1 Accelerator pedal position F
4C 76 1 Commanded throttle actuator
4D 77 2 Time run with MIL on 0 65,535 min
4E 78 2 Time since trouble codes cleared
4F 79 4 Maximum value for Fuel–Air equivalence ratio, oxygen sensor voltage, oxygen sensor current, and intake manifold absolute pressure 0, 0, 0, 0 255, 255, 255, 2550 ratio, V, mA, kPa , , ,
50 80 4 Maximum value for air flow rate from mass air flow sensor 0 2550 g/s ; , , and are reserved for future use
51 81 1 Fuel Type From fuel type table see below
52 82 1 Ethanol fuel % 0 100 %
53 83 2 Absolute Evap system Vapor Pressure 0 327.675 kPa
54 84 2 Evap system vapor pressure -32,768 32,767 Pa (AB is two's complement signed)[3]
55 85 2 Short term secondary oxygen sensor trim, A: bank 1, B: bank 3 -100 99.2 %

56 86 2 Long term secondary oxygen sensor trim, A: bank 1, B: bank 3
57 87 2 Short term secondary oxygen sensor trim, A: bank 2, B: bank 4
58 88 2 Long term secondary oxygen sensor trim, A: bank 2, B: bank 4
59 89 2 Fuel rail absolute pressure 0 655,350 kPa
5A 90 1 Relative accelerator pedal position 0 100 %
5B 91 1 Hybrid battery pack remaining life 0 100 %
5C 92 1 Engine oil temperature -40 210 °C
5D 93 2 Fuel injection timing -210.00 301.992 °
5E 94 2 Engine fuel rate 0 3212.75 L/h
5F 95 1 Emission requirements to which vehicle is designed Bit Encoded
60 96 4 PIDs supported [$61 - $80] Bit encoded [A7..D0] == [PID $61..PID $80] See below
61 97 1 Driver's demand engine - percent torque -125 130 %
62 98 1 Actual engine - percent torque -125 130 %
63 99 2 Engine reference torque 0 65,535 N⋅m
64 100 5 Engine percent torque data -125 130 % Idle
Engine point 1
Engine point 2
Engine point 3
Engine point 4
65 101 2 Auxiliary input / output supported Bit Encoded
66 102 5 Mass air flow sensor 0 2047.96875 g/s [A0]== Sensor A Supported
[A1]== Sensor B Supported
Sensor A:
Sensor B:
67 103 3 Engine coolant temperature -40 215 °C [A0]== Sensor 1 Supported
[A1]== Sensor 2 Supported
Sensor 1:
Sensor 2:
68 104 3 Intake air temperature sensor -40 215 °C [A0]== Sensor 1 Supported
[A1]== Sensor 2 Supported
Sensor 1:
Sensor 2:
69 105 7 Actual EGR, Commanded EGR, and EGR Error
6A 106 5 Commanded Diesel intake air flow control and relative intake air flow position
6B 107 5 Exhaust gas recirculation temperature
6C 108 5 Commanded throttle actuator control and relative throttle position
6D 109 11 Fuel pressure control system
6E 110 9 Injection pressure control system
6F 111 3 Turbocharger compressor inlet pressure
70 112 10 Boost pressure control
71 113 6 Variable Geometry turbo (VGT) control
72 114 5 Wastegate control
73 115 5 Exhaust pressure
74 116 5 Turbocharger RPM
75 117 7 Turbocharger temperature
76 118 7 Turbocharger temperature
77 119 5 Charge air cooler temperature (CACT)
78 120 9 Exhaust Gas temperature (EGT) Bank 1 Special PID. See below
79 121 9 Exhaust Gas temperature (EGT) Bank 2 Special PID. See below
7A 122 7 Diesel particulate filter (DPF)

differential pressure

7B 123 7 Diesel particulate filter (DPF)
7C 124 9 Diesel Particulate filter (DPF) temperature °C
7D 125 1 NOx NTE (Not-To-Exceed) control area status
7E 126 1 PM NTE (Not-To-Exceed) control area status
7F 127 13 Engine run time [b] s
80 128 4 PIDs supported [$81 - $A0] Bit encoded [A7..D0] == [PID $81..PID $A0] See below
81 129 41 Engine run time for Auxiliary Emissions Control Device(AECD)
82 130 41 Engine run time for Auxiliary Emissions Control Device(AECD)
83 131 9 NOx sensor
84 132 1 Manifold surface temperature
85 133 10 NOx reagent system %
86 134 5 Particulate matter (PM) sensor
87 135 5 Intake manifold absolute pressure
88 136 13 SCR Induce System
89 137 41 Run Time for AECD #11-#15
8A 138 41 Run Time for AECD #16-#20
8B 139 7 Diesel Aftertreatment
8C 140 17 O2 Sensor (Wide Range)
8D 141 1 Throttle Position G 0 100 %
8E 142 1 Engine Friction - Percent Torque -125 130 %
8F 143 7 PM Sensor Bank 1 & 2
90 144 3 WWH-OBD Vehicle OBD System Information h
91 145 5 WWH-OBD Vehicle OBD System Information h
92 146 2 Fuel System Control
93 147 3 WWH-OBD Vehicle OBD Counters support h
94 148 12 NOx Warning And Inducement System
98 152 9 Exhaust Gas Temperature Sensor
99 153 9 Exhaust Gas Temperature Sensor
9A 154 6 Hybrid/EV Vehicle System Data, Battery, Voltage
9B 155 4 Diesel Exhaust Fluid Sensor Data %
9C 156 17 O2 Sensor Data
9D 157 4 Engine Fuel Rate g/s
9E 158 2 Engine Exhaust Flow Rate kg/h
9F 159 9 Fuel System Percentage Use
A0 160 4 PIDs supported [$A1 - $C0] Bit encoded [A7..D0] == [PID $A1..PID $C0] See below
A1 161 9 NOx Sensor Corrected Data ppm
A2 162 2 Cylinder Fuel Rate 0 2047.96875 mg/stroke
A3 163 9 Evap System Vapor Pressure Pa
A4 164 4 Transmission Actual Gear 0 65.535 ratio [A1]==Supported

A5 165 4 Commanded Diesel Exhaust Fluid Dosing 0 127.5 % [A0]= 1:Supported; 0:Unsupported

A6 166 4 Odometer [c] 0 429,496,729.5 km
A7 167 4 NOx Sensor Concentration Sensors 3 and 4
A8 168 4 NOx Sensor Corrected Concentration Sensors 3 and 4
A9 169 4 ABS Disable Switch State [A0]= 1:Supported; 0:Unsupported

[B0]= 1:Yes;0:No

C0 192 4 PIDs supported [$C1 - $E0] Bit encoded [A7..D0] == [PID $C1..PID $E0] See below
C3 195 2 Fuel Level Input A/B 0 25,700 % Returns numerous data, including Drive Condition ID and Engine Speed*
C4 196 8 Exhaust Particulate Control System Diagnostic Time/Count 0 4,294,967,295 seconds / Count B5 is Engine Idle Request
B6 is Engine Stop Request*
First byte = Time in seconds
Second byte = Count
C5 197 4 Fuel Pressure A and B 0 5,177 kPa
C6 198 7 Byte 1 - Particulate control - driver inducement system status
Byte 2,3 - Removal or block of the particulate aftertreatment system counter
Byte 4,5 - Liquid regent injection system (e.g. fuel-borne catalyst) failure counter
Byte 6,7 - Malfunction of Particulate control monitoring system counter
0 65,535 h
C7 199 2 Distance Since Reflash or Module Replacement 0 65,535 km
C8 200 1 NOx Control Diagnostic (NCD) and Particulate Control Diagnostic (PCD) Warning Lamp status - - Bit
PID
(hex)
PID
(Dec)
Data bytes returned Description Min value Max value Units Formula[a]

Service 02 - Show freeze frame data

[edit]

Service 02 accepts the same PIDs as service 01, with the same meaning,[5] but information given is from when the freeze frame[6] was created. Note that PID $02 is used to obtain the DTC that triggered the freeze frame.

A person has to send the frame number in the data section of the message.

Service 03 - Show stored Diagnostic Trouble Codes (DTCs)

[edit]
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]
N/A n*6 Request trouble codes 3 codes per message frame. See below

Service 04 - Clear Diagnostic Trouble Codes and stored values

[edit]
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]
N/A 0 Clear trouble codes / Malfunction indicator lamp (MIL) / Check engine light Clears all stored trouble codes and turns the MIL off.

Service 05 - Test results, oxygen sensor monitoring (non CAN only)

[edit]
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]
0100 4 OBD Monitor IDs supported ($01 – $20) 0x0 0xffffffff
0101 2 O2 Sensor Monitor Bank 1 Sensor 1 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0102 O2 Sensor Monitor Bank 1 Sensor 2 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0103 O2 Sensor Monitor Bank 1 Sensor 3 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0104 O2 Sensor Monitor Bank 1 Sensor 4 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0105 O2 Sensor Monitor Bank 2 Sensor 1 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0106 O2 Sensor Monitor Bank 2 Sensor 2 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0107 O2 Sensor Monitor Bank 2 Sensor 3 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0108 O2 Sensor Monitor Bank 2 Sensor 4 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0109 O2 Sensor Monitor Bank 3 Sensor 1 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010A O2 Sensor Monitor Bank 3 Sensor 2 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010B O2 Sensor Monitor Bank 3 Sensor 3 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010C O2 Sensor Monitor Bank 3 Sensor 4 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010D O2 Sensor Monitor Bank 4 Sensor 1 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010E O2 Sensor Monitor Bank 4 Sensor 2 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
010F O2 Sensor Monitor Bank 4 Sensor 3 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0110 O2 Sensor Monitor Bank 4 Sensor 4 0.00 1.275 V 0.005 Rich to lean sensor threshold voltage
0201 O2 Sensor Monitor Bank 1 Sensor 1 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0202 O2 Sensor Monitor Bank 1 Sensor 2 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0203 O2 Sensor Monitor Bank 1 Sensor 3 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0204 O2 Sensor Monitor Bank 1 Sensor 4 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0205 O2 Sensor Monitor Bank 2 Sensor 1 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0206 O2 Sensor Monitor Bank 2 Sensor 2 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0207 O2 Sensor Monitor Bank 2 Sensor 3 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0208 O2 Sensor Monitor Bank 2 Sensor 4 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0209 O2 Sensor Monitor Bank 3 Sensor 1 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020A O2 Sensor Monitor Bank 3 Sensor 2 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020B O2 Sensor Monitor Bank 3 Sensor 3 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020C O2 Sensor Monitor Bank 3 Sensor 4 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020D O2 Sensor Monitor Bank 4 Sensor 1 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020E O2 Sensor Monitor Bank 4 Sensor 2 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
020F O2 Sensor Monitor Bank 4 Sensor 3 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
0210 O2 Sensor Monitor Bank 4 Sensor 4 0.00 1.275 V 0.005 Lean to Rich sensor threshold voltage
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]

Service 09 - Request vehicle information

[edit]
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]
00 4 Service 9 supported PIDs ($01 to $20) Bit encoded. [A7..D0] = [PID $01..PID $20] See below
01 1 VIN Message Count in PID 02. Only for ISO 9141-2, ISO 14230-4 and SAE J1850. Usually the value will be 5.
02 17 Vehicle Identification Number (VIN) 17-char VIN, ASCII-encoded and left-padded with null chars (0x00) if needed to.
03 1 Calibration ID message count for PID 04. Only for ISO 9141-2, ISO 14230-4 and SAE J1850. It will be a multiple of 4 (4 messages are needed for each ID).
04 16,32,48,64.. Calibration ID Up to 16 ASCII chars. Data bytes not used will be reported as null bytes (0x00). Several CALID can be outputed (16 bytes each)
05 1 Calibration verification numbers (CVN) message count for PID 06. Only for ISO 9141-2, ISO 14230-4 and SAE J1850.
06 4,8,12,16 Calibration Verification Numbers (CVN) Several CVN can be output (4 bytes each) the number of CVN and CALID must match Raw data left-padded with null characters (0x00). Usually displayed as hex string.
07 1 In-use performance tracking message count for PID 08 and 0B. Only for ISO 9141-2, ISO 14230-4 and SAE J1850. 8 10 8 if sixteen values are required to be reported, 9 if eighteen values are required to be reported, and 10 if twenty values are required to be reported (one message reports two values, each one consisting in two bytes).
08 4 In-use performance tracking for spark ignition vehicles 4 or 5 messages, each one containing 4 bytes (two values). See below
09 1 ECU name message count for PID 0A
0A 20 ECU name ASCII-coded. Right-padded with null chars (0x00).
0B 4 In-use performance tracking for compression ignition vehicles 5 messages, each one containing 4 bytes (two values). See below
PID
(hex)
Data bytes returned Description Min value Max value Units Formula[a]
  1. ^ a b c d e f g h In the formula column, letters A, B, C, etc. represent the first, second, third, etc. byte of the data. For example, for two data bytes 0F 19, A = 0F and B = 19. Where a (?) appears, contradictory or incomplete information was available.
  2. ^ Starting with MY 2010 the California Air Resources Board mandated that all diesel vehicles must supply total engine hours [4]
  3. ^ Starting with MY 2019 the California Air Resources Board mandated that all vehicles must supply odometer[4]

Bitwise encoded PIDs

[edit]

Some of the PIDs in the above table cannot be explained with a simple formula. A more elaborate explanation of these data is provided here:

Service 01 PID 00 - Show PIDs supported

[edit]

A request for this PID returns 4 bytes of data (Big-endian). Each bit, from MSB to LSB, represents one of the next 32 PIDs and specifies whether that PID is supported.

For example, if the car response is BE1FA813, it can be decoded like this:

Hexadecimal B E 1 F A 8 1 3
Binary 1 0 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 1 0 1 0 0 0 0 0 0 1 0 0 1 1
Supported? Yes No Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No Yes No Yes No No No No No No Yes No No Yes Yes
PID number 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20

So, supported PIDs are: 01, 03, 04, 05, 06, 07, 0C, 0D, 0E, 0F, 10, 11, 13, 15, 1C, 1F and 20

Service 01 PID 01 - Monitor status since DTCs cleared

[edit]

A request for this PID returns 4 bytes of data, labeled A, B, C and D.

The first byte (A) contains two pieces of information. Bit A7 (MSB of byte A) indicates whether or not the MIL (malfunction indicator light, aka. check engine light) is illuminated. Bits A6 through A0 represent the number of diagnostic trouble codes currently flagged in the ECU.

The second, third, and fourth bytes (B, C and D) give information about the availability and completeness of certain on-board tests ("OBD readiness checks"). The third and fourth bytes are to be interpreted differently depending upon whether the engine is spark ignition (e.g. Otto or Wankel engines) or compression ignition (e.g. Diesel engines). In the second byte (B), bit 3 indicates the engine type and thus how to interpret bytes C and D, with 0 being spark (Otto or Wankel) and 1 (set) being compression (Diesel). Bits B6 to B4 and B2 to B0 are used for information about tests that not engine-type specific, and thus termed common tests. Note that for bits indicating test availability a bit set to 1 indicates available, whilst for bits indicating test completeness a bit set to 0 indicates complete.

Bits Definition
A7 State of the CEL/MIL (on/off).
A6-A0 Number of confirmed emissions-related DTCs available for display.
B7 Reserved (should be 0)
B6-B4 Bitmap indicating completeness of common tests.
B3 Indication of engine type
0 = Spark ignition (e.g. Otto or Wankel engines)
1 = Compression ignition (e.g. Diesel engines)
B2-B0 Bitmap indicating availability of common tests.
C7-C0 Bitmap indicating availability of engine-type specific tests.
D7-D0 Bitmap indicating completeness of engine-type specific tests.

Bits from byte B representing common test indicators (those not engine-type specific) are mapped as follows:

Test availability Test completeness
Components B2 B6
Fuel System B1 B5
Misfire B0 B4

Bytes C and D are mapped as follows for spark ignition engine types (e.g. Otto or Wankel engines):

Test availability Test completeness
EGR and/or VVT System C7 D7
Oxygen Sensor Heater C6 D6
Oxygen Sensor C5 D5
Gasoline Particulate Filter[a] C4 D4
Secondary Air System C3 D3
Evaporative System C2 D2
Heated Catalyst C1 D1
Catalyst C0 D0

Bytes C and D are alternatively mapped as follows for compression ignition engine types (Diesel engines):

Test availability Test completeness
EGR and/or VVT System C7 D7
PM filter monitoring C6 D6
Exhaust Gas Sensor C5 D5
- Reserved - C4 D4
Boost Pressure C3 D3
- Reserved - C2 D2
NOx/SCR Monitor C1 D1
NMHC Catalyst[b] C0 D0
  1. ^ A common misconception is that C4/D4 was A/C Refrigerant, however it had been listed as Reserved in J1979 for years, and was recently defined as GPF.
  2. ^ NMHC may stand for Non-Methane HydroCarbons, but J1979 does not enlighten us. The translation would be the ammonia sensor in the SCR catalyst.

Service 01 PID 41 - Monitor status this drive cycle

[edit]

A request for this PID returns 4 bytes of data. The data returned is of an identical form to that returned for PID 01, with one exception - the first byte is always zero.

Service 01 PID 78 and 79 - Exhaust Gas temperature (EGT) Bank 1 and Bank 2

[edit]

A request for one of these two PIDs will return 9 bytes of data. PID 78 returns data relating to EGT sensors for bank 1, whilst PID 79 similarly returns data for bank 2. The first byte is a bit encoded field indicating which EGT sensors are supported for the respective bank.

Bytes Description
A EGT sensor support
B-C Temperature read by EGT sensor 1
D-E Temperature read by EGT sensor 2
F-G Temperature read by EGT sensor 3
H-I Temperature read by EGT sensor 4

The first byte is bit-encoded as follows:

Bits Description
A7-A4 Reserved
A3 EGT sensor 4 supported?
A2 EGT sensor 3 supported?
A1 EGT sensor 2 supported?
A0 EGT sensor 1 supported?

Bytes B through I provide 16-bit integers indicating the temperatures of the sensors. The temperature values are interpreted in degrees Celsius in the range -40 to 6513.5 (scale 0.1), using the usual formula (MSB is A, LSB is B). Only values for which the corresponding sensor is supported are meaningful.

Service 03 (no PID required) - Show stored Diagnostic Trouble Codes

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A request for this service returns a list of the DTCs that have been set. The list is encapsulated using the ISO 15765-2 protocol.

If there are two or fewer DTCs (up to 4 bytes) then they are returned in an ISO-TP Single Frame (SF). Three or more DTCs in the list are reported in multiple frames, with the exact count of frames dependent on the communication type and addressing details.

Each trouble code requires 2 bytes to describe. Encoded in these bytes are a category and a number. It is typically shown decoded into a five-character form like "U0158", where the first character (here 'U') represents the category the DTC belongs to, and the remaining four characters are a hexadecimal representation of the number under that category. The first two bits (A7 and A6) of the first byte (A) represent the category. The remaining 14 bits represent the number. Of note is that since the second character is formed from only two bits, it can thus only be within the range 0-3.

Bits Definition
A7-A6 Category
00: P - Powertrain
01: C - Chassis
10: B - Body
11: U - Network[a]
A5-B0 Number (within category)
  1. ^ Whilst this is commonly referred to as the network category, it may originally have been the 'undefined' category, hence the use of the letter 'U' rather than 'N'.

An example DTC of "U0158" would be decoded as follows:

Bit A7 A6 A5 A4 A3 A2 A1 A0 B7 B6 B5 B4 B3 B2 B1 B0
Binary 1 1 0 0 0 0 0 1 0 1 0 1 1 0 0 0
Hexadecimal C 1 5 8
Decoded DTC U 0 1 5 8

The resulting five-character code, e.g. "U0158", can be looked up in a table of OBD-II DTCs to get an actual description of what it represents. Of note, whilst some blocks of DTC code ranges have generic meanings that apply to all vehicles and manufacturers, the meanings of others can vary per manufacturer or even model.

It is also worth noting that DTCs may sometimes be encountered in a four-character form, e.g. "C158", which is simply the plain hexadecimal representation of the two bytes, with proper decoding with respect to the category not having been performed.

Service 09 PID 08 - In-use performance tracking for spark ignition engines

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It provides information about track in-use performance for catalyst banks, oxygen sensor banks, evaporative leak detection systems, EGR systems and secondary air system.

The numerator for each component or system tracks the number of times that all conditions necessary for a specific monitor to detect a malfunction have been encountered. The denominator for each component or system tracks the number of times that the vehicle has been operated in the specified conditions.

The count of data items should be reported at the beginning (the first byte).

All data items of the In-use Performance Tracking record consist of two bytes and are reported in this order (each message contains two items, hence the message length is 4).

Mnemonic Description
OBDCOND OBD Monitoring Conditions Encountered Counts
IGNCNTR Ignition Counter
CATCOMP1 Catalyst Monitor Completion Counts Bank 1
CATCOND1 Catalyst Monitor Conditions Encountered Counts Bank 1
CATCOMP2 Catalyst Monitor Completion Counts Bank 2
CATCOND2 Catalyst Monitor Conditions Encountered Counts Bank 2
O2SCOMP1 O2 Sensor Monitor Completion Counts Bank 1
O2SCOND1 O2 Sensor Monitor Conditions Encountered Counts Bank 1
O2SCOMP2 O2 Sensor Monitor Completion Counts Bank 2
O2SCOND2 O2 Sensor Monitor Conditions Encountered Counts Bank 2
EGRCOMP EGR Monitor Completion Condition Counts
EGRCOND EGR Monitor Conditions Encountered Counts
AIRCOMP AIR Monitor Completion Condition Counts (Secondary Air)
AIRCOND AIR Monitor Conditions Encountered Counts (Secondary Air)
EVAPCOMP EVAP Monitor Completion Condition Counts
EVAPCOND EVAP Monitor Conditions Encountered Counts
SO2SCOMP1 Secondary O2 Sensor Monitor Completion Counts Bank 1
SO2SCOND1 Secondary O2 Sensor Monitor Conditions Encountered Counts Bank 1
SO2SCOMP2 Secondary O2 Sensor Monitor Completion Counts Bank 2
SO2SCOND2 Secondary O2 Sensor Monitor Conditions Encountered Counts Bank 2

Service 09 PID 0B - In-use performance tracking for compression ignition engines

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It provides information about track in-use performance for NMHC catalyst, NOx catalyst monitor, NOx adsorber monitor, PM filter monitor, exhaust gas sensor monitor, EGR/ VVT monitor, boost pressure monitor and fuel system monitor.

All data items consist of two bytes and are reported in this order (each message contains two items, hence message length is 4):

Mnemonic Description
OBDCOND OBD Monitoring Conditions Encountered Counts
IGNCNTR Ignition Counter
HCCATCOMP NMHC Catalyst Monitor Completion Condition Counts
HCCATCOND NMHC Catalyst Monitor Conditions Encountered Counts
NCATCOMP NOx/SCR Catalyst Monitor Completion Condition Counts
NCATCOND NOx/SCR Catalyst Monitor Conditions Encountered Counts
NADSCOMP NOx Adsorber Monitor Completion Condition Counts
NADSCOND NOx Adsorber Monitor Conditions Encountered Counts
PMCOMP PM Filter Monitor Completion Condition Counts
PMCOND PM Filter Monitor Conditions Encountered Counts
EGSCOMP Exhaust Gas Sensor Monitor Completion Condition Counts
EGSCOND Exhaust Gas Sensor Monitor Conditions Encountered Counts
EGRCOMP EGR and/or VVT Monitor Completion Condition Counts
EGRCOND EGR and/or VVT Monitor Conditions Encountered Counts
BPCOMP Boost Pressure Monitor Completion Condition Counts
BPCOND Boost Pressure Monitor Conditions Encountered Counts
FUELCOMP Fuel Monitor Completion Condition Counts
FUELCOND Fuel Monitor Conditions Encountered Counts

Enumerated PIDs

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Some PIDs are to be interpreted specially, and aren't necessarily exactly bitwise encoded, or in any scale. The values for these PIDs are enumerated.

Service 01 PID 03 - Fuel system status

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A request for this PID returns 2 bytes of data. The first byte describes fuel system #1. The second byte describes fuel system #2 (if it exists) and is encoded identically to the first byte. The meaning assigned to the value of each byte is as follows:

Value Description
0 The motor is off
1 Open loop due to insufficient engine temperature
2 Closed loop, using oxygen sensor feedback to determine fuel mix
4 Open loop due to engine load OR fuel cut due to deceleration
8 Open loop due to system failure
16 Closed loop, using at least one oxygen sensor but there is a fault in the feedback system

Any other value is an invalid response.

Service 01 PID 12 - Commanded secondary air status

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A request for this PID returns a single byte of data which describes the secondary air status.

Value Description
1 Upstream
2 Downstream of catalytic converter
4 From the outside atmosphere or off
8 Pump commanded on for diagnostics

Any other value is an invalid response.

Service 01 PID 1C - OBD standards this vehicle conforms to

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A request for this PID returns a single byte of data which describes which OBD standards this ECU was designed to comply with. The different values the data byte can hold are shown below, next to what they mean:

Value Description
1 OBD-II as defined by the CARB
2 OBD as defined by the EPA
3 OBD and OBD-II
4 OBD-I
5 Not OBD compliant
6 EOBD (Europe)
7 EOBD and OBD-II
8 EOBD and OBD
9 EOBD, OBD and OBD II
10 JOBD (Japan)
11 JOBD and OBD II
12 JOBD and EOBD
13 JOBD, EOBD, and OBD II
14 Reserved
15 Reserved
16 Reserved
17 Engine Manufacturer Diagnostics (EMD)
18 Engine Manufacturer Diagnostics Enhanced (EMD+)
19 Heavy Duty On-Board Diagnostics (Child/Partial) (HD OBD-C)
20 Heavy Duty On-Board Diagnostics (HD OBD)
21 World Wide Harmonized OBD (WWH OBD)
22 Reserved
23 Heavy Duty Euro OBD Stage I without NOx control (HD EOBD-I)
24 Heavy Duty Euro OBD Stage I with NOx control (HD EOBD-I N)
25 Heavy Duty Euro OBD Stage II without NOx control (HD EOBD-II)
26 Heavy Duty Euro OBD Stage II with NOx control (HD EOBD-II N)
27 Reserved
28 Brazil OBD Phase 1 (OBDBr-1)
29 Brazil OBD Phase 2 (OBDBr-2)
30 Korean OBD (KOBD)
31 India OBD I (IOBD I)
32 India OBD II (IOBD II)
33 Heavy Duty Euro OBD Stage VI (HD EOBD-IV)
34-250 Reserved
251-255 Not available for assignment (SAE J1939 special meaning)

Service 01 PID 51 - Fuel Type Coding

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This PID returns a value from an enumerated list giving the fuel type of the vehicle. The fuel type is returned as a single byte, and the value is given by the following table:

Value Description
0 Not available
1 Gasoline
2 Methanol
3 Ethanol
4 Diesel
5 LPG
6 CNG
7 Propane
8 Electric
9 Bifuel running Gasoline
10 Bifuel running Methanol
11 Bifuel running Ethanol
12 Bifuel running LPG
13 Bifuel running CNG
14 Bifuel running Propane
15 Bifuel running Electricity
16 Bifuel running electric and combustion engine
17 Hybrid gasoline
18 Hybrid Ethanol
19 Hybrid Diesel
20 Hybrid Electric
21 Hybrid running electric and combustion engine
22 Hybrid Regenerative
23 Bifuel running diesel

Any other value is reserved by ISO/SAE. There are currently no definitions for flexible-fuel vehicle.

Non-standard PIDs

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The majority of all OBD-II PIDs in use are non-standard. For most modern vehicles, there are many more functions supported on the OBD-II interface than are covered by the standard PIDs, and there is relatively minor overlap between vehicle manufacturers for these non-standard PIDs.

There is very limited information available in the public domain for non-standard PIDs. The primary source of information on non-standard PIDs across different manufacturers is maintained by the US-based Equipment and Tool Institute and only available to members. The price of ETI membership for access to scan codes varies based on company size defined by annual sales of automotive tools and equipment in North America:

Annual Sales in North America Annual Dues
Under $10,000,000 $5,000
$10,000,000 - $50,000,000 $7,500
Greater than $50,000,000 $10,000

However, even ETI membership will not provide full documentation for non-standard PIDs. ETI states:[7][8]

Some OEMs refuse to use ETI as a one-stop source of scan tool information. They prefer to do business with each tool company separately. These companies also require that you enter into a contract with them. The charges vary but here is a snapshot as of April 13th, 2015 of the per year charges:

GM $50,000
Honda $5,000
Suzuki $1,000
BMW $25,500 plus $2,000 per update. Updates occur annually.

CAN (11-bit) bus format

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As defined in ISO 15765-4, emissions protocols (including OBD-II, EOBD, UDS, etc.) use the ISO-TP transport layer (ISO 15765-2). All CAN frames sent using ISO-TP use a data length of 8 bytes (and DLC of 8). It is recommended to pad the unused data bytes with 0xCC.

The PID query and response occurs on the vehicle's CAN bus. Standard OBD requests and responses use functional addresses. The diagnostic reader initiates a query using CAN ID 7DFh, which acts as a broadcast address, and accepts responses from any ID in the range 7E8h to 7EFh. ECUs that can respond to OBD queries listen both to the functional broadcast ID of 7DFh and one assigned ID in the range 7E0h to 7E7h. Their response has an ID of their assigned ID plus 8 e.g. 7E8h through 7EFh.

This approach allows up to eight ECUs, each independently responding to OBD queries. The diagnostic reader can use the ID in the ECU response frame to continue communication with a specific ECU. In particular, multi-frame communication requires a response to the specific ECU ID rather than to ID 7DFh.

CAN bus may also be used for communication beyond the standard OBD messages. Physical addressing uses particular CAN IDs for specific modules (e.g., 720h for the instrument cluster in Fords) with proprietary frame payloads.

Query

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The functional PID query is sent to the vehicle on the CAN bus at ID 7DFh, using 8 data bytes. The bytes are:

Byte
PID Type 0 1 2 3 4 5 6 7
SAE Standard Number of
additional
data bytes:
2
Service
01 = show current data;
02 = freeze frame;
etc.
PID code
(e.g.: 05 = Engine coolant temperature)
not used
(ISO 15765-2 suggests CCh)
Vehicle specific Number of
additional
data bytes:
3
Custom service: (e.g.: 22 = enhanced data) PID code
(e.g.: 4980h)
not used
(ISO 15765-2 suggests CCh)

Response

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The vehicle responds to the PID query on the CAN bus with message IDs that depend on which module responded. Typically the engine or main ECU responds at ID 7E8h. Other modules, like the hybrid controller or battery controller in a Prius, respond at 07E9h, 07EAh, 07EBh, etc. These are 8h higher than the physical address the module responds to. Even though the number of bytes in the returned value is variable, the message uses 8 data bytes regardless (CAN bus protocol form Frameformat with 8 data bytes). The bytes are:

Byte
CAN Address 0 1 2 3 4 5 6 7
SAE Standard
7E8h,
7E9h,
7EAh,
etc.
Number of
additional
data bytes:
3 to 6
Custom service
Same as query, except that 40h is added to the service value. So:
41h = show current data;
42h = freeze frame;
etc.
PID code
(e.g.: 05 = Engine coolant temperature)
value of the specified parameter, byte 0 value, byte 1 (optional) value, byte 2 (optional) value, byte 3 (optional) not used
(may be 00h or 55h)
Vehicle specific
7E8h, or 8h + physical ID of module.
Number of
additional
data bytes:
4to 7
Custom service: same as query, except that 40h is added to the service value.(e.g.: 62h = response to service 22h request) PID code
(e.g.: 4980h)
value of the specified parameter, byte 0 value, byte 1 (optional) value, byte 2 (optional) value, byte 3 (optional)
Vehicle specific
7E8h, or 8h + physical ID of module.
Number of
additional
data bytes:
3
7Fh this a general response usually indicating the module doesn't recognize the request. Custom service: (e.g.: 22h = enhanced diagnostic data by PID, 21h = enhanced data by offset) 31h not used
(may be 00h)

See also

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References

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  1. ^ a b "Basic Information | On-Board Diagnostics (OBD)". US EPA. 16 March 2015. Retrieved 24 June 2015.
  2. ^ "Escape PHEV TechInfo - PIDs". Electric Auto Association - Plug in Hybrid Electric Vehicle. Retrieved 11 December 2013.
  3. ^ a b "Extended PID's - Signed Variables". Torque-BHP. Retrieved 17 March 2016.
  4. ^ a b "Final Regulation Order" (PDF). US: California Air Resources Board. 2015. Retrieved 4 September 2021.
  5. ^ "OBD2 Codes and Meanings". Lithuania: Baltic Automotive Diagnostic Systems. Retrieved 11 June 2020.
  6. ^ "OBD2 Freeze Frame Data: What is It? How To Read It?". OBD Advisor. 2018-02-28. Retrieved 2020-03-14.
  7. ^ "ETI Full Membership FAQ". The Equipment and Tool Institute. Retrieved 29 November 2013. showing cost of access to OBD-II PID documentation
  8. ^ "Special OEM License Requirements". The Equipment and Tool Institute. Retrieved 13 April 2015.

Further reading

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