OBD-II PIDs Codes Explained
OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool. SAE standard J/1979 defines many PIDs, but manufacturers also define many more PIDs specific to their vehicles. All light duty vehicles (i.e. less than 8,500 pounds) sold in North America since 1996, as well as medium duty vehicles (i.e. 8,500-14,000 pounds) beginning in 2005, and heavy duty vehicles (i.e. greater than 14,000 pounds) beginning in 2010, are required to support OBD-II diagnostics, using a standardized data link connector, and a subset of the SAE J/1979 defined PIDs (or SAE J/1939 as applicable for medium/heavy duty vehicles), primarily for state mandated emissions inspections.
Typically, an automotive technician will use PIDs with a scan tool connected to the vehicle's OBD-II connector.
- The technician enters the PID
- The scan tool sends it to the vehicle's bus (CAN, VPW, PWM, ISO, KWP. After 2008, CAN only)
- A device on the bus recognizes the PID as one it is responsible for, and reports the value for that PID to the bus
- The scan tool reads the response, and displays it to the technician
Modes
There are ten modes of operation described in the latest OBD-II standard SAE J1979. They are as follows (the $ prefix indicates a hexadecimal radix): $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 DTC's (Cleared DTC's)
Vehicle manufacturers are not required to support all modes.
Each manufacturer may define additional modes above #9 (e.g.: mode 22 as defined by SAE J2190 for Ford/GM, mode 21 for Toyota) for other information (e.g.: the voltage of the Traction Battery in a HEV).
Standard PIDs
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 modes 1 and 2 are basically identical, except that Mode 1 provides current information, whereas Mode 2 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 Mode 1, and PID 02, which is only available in Mode 2. If Mode 2 PID 02 returns zero, then there is no snapshot and all other Mode 2 data is meaningless.
Please, note that when using Bit-Encoded-Notation, quantities like C4 means bit 4 from data byte C. Each bit is numerated from 0 to 7, so 7 is the most significant bit and 0 is the least significant bit.
| Mode (hex) | PID (hex) | Data bytes returned | Description | Min value | Max value | Units | Formula |
|---|---|---|---|---|---|---|---|
| 01 | 00 | 4 | PIDs supported [01 - 20] | Bit encoded [A7..D0] == [PID $01..PID $20] See below. | |||
| 01 | 01 | 4 | Monitor status since DTCs cleared. (Includes malfunction indicator lamp (MIL) status and number of DTCs.) | Bit encoded. See below. | |||
| 01 | 02 | 2 | Freeze DTC | ||||
| 01 | 03 | 2 | Fuel system status | Bit encoded. See below. | |||
| 01 | 04 | 1 | Calculated engine load value | 0 | 100 | % | A*100/255 |
| 01 | 05 | 1 | Engine coolant temperature | -40 | 215 | °C | A-40 |
| 01 | 06 | 1 | Short term fuel % trim—Bank 1 | -100 Subtracting Fuel (Rich Condition) | 99.22 Adding Fuel (Lean Condition) | % | (A-128) * 100/128 |
| 01 | 07 | 1 | Long term fuel % trim—Bank 1 | -100 Subtracting Fuel (Rich Condition) | 99.22 Adding Fuel (Lean Condition) | % | (A-128) * 100/128 |
| 01 | 08 | 1 | Short term fuel % trim—Bank 2 | -100 Subtracting Fuel (Rich Condition) | 99.22 Adding Fuel (Lean Condition) | % | (A-128) * 100/128 |
| 01 | 09 | 1 | Long term fuel % trim—Bank 2 | -100 Subtracting Fuel (Rich Condition) | 99.22 Adding Fuel (Lean Condition) | % | (A-128) * 100/128 |
| 01 | 0A | 1 | Fuel pressure | 0 | 765 | kPa (gauge) | A*3 |
| 01 | 0B | 1 | Intake manifold absolute pressure | 0 | 255 | kPa (absolute) | A |
| 01 | 0C | 2 | Engine RPM | 0 | 16,383.75 | rpm | ((A*256)+B)/4 |
| 01 | 0D | 1 | Vehicle speed | 0 | 255 | km/h | A |
| 01 | 0E | 1 | Timing advance | -64 | 63.5 | ° relative to #1 cylinder | A/2 - 64 |
| 01 | 0F | 1 | Intake air temperature | -40 | 215 | °C | A-40 |
| 01 | 10 | 2 | MAF air flow rate | 0 | 655.35 | grams/sec | ((A*256)+B) / 100 |
| 01 | 11 | 1 | Throttle position | 0 | 100 | % | A*100/255 |
| 01 | 12 | 1 | Commanded secondary air status | Bit encoded. See below. | |||
| 01 | 13 | 1 | Oxygen sensors present | [A0..A3] == Bank 1, Sensors 1-4. [A4..A7] == Bank 2... | |||
| 01 | 14 | 2 | Bank 1, Sensor 1: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 15 | 2 | Bank 1, Sensor 2: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 16 | 2 | Bank 1, Sensor 3: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 17 | 2 | Bank 1, Sensor 4: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 18 | 2 | Bank 2, Sensor 1: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 19 | 2 | Bank 2, Sensor 2: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 1A | 2 | Bank 2, Sensor 3: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 1B | 2 | Bank 2, Sensor 4: Oxygen sensor voltage, Short term fuel trim | 0 -100(lean) | 1.275 99.2(rich) | Volts % | A/200 (B-128) * 100/128 (if B==$FF, sensor is not used in trim calc) |
| 01 | 1C | 1 | OBD standards this vehicle conforms to | Bit encoded. See below. | |||
| 01 | 1D | 1 | Oxygen sensors present | Similar to PID 13, but [A0..A7] == [B1S1, B1S2, B2S1, B2S2, B3S1, B3S2, B4S1, B4S2] | |||
| 01 | 1E | 1 | Auxiliary input status | A0 == Power Take Off (PTO) status (1 == active) [A1..A7] not used | |||
| 01 | 1F | 2 | Run time since engine start | 0 | 65,535 | seconds | (A*256)+B |
| 01 | 20 | 4 | PIDs supported [21 - 40] | Bit encoded [A7..D0] == [PID $21..PID $40] See below. | |||
| 01 | 21 | 2 | Distance traveled with malfunction indicator lamp (MIL) on | 0 | 65,535 | km | (A*256)+B |
| 01 | 22 | 2 | Fuel Rail Pressure (relative to manifold vacuum) | 0 | 5177.265 | kPa | ((A*256)+B) * 0.079 |
| 01 | 23 | 2 | Fuel Rail Pressure (diesel, or gasoline direct inject) | 0 | 655,350 | kPa (gauge) | ((A*256)+B) * 10 |
| 01 | 24 | 4 | O2S1_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 1.999 7.999 | N/A V | ((A*256)+B)*2/65535 or ((A*256)+B)/32768 ((C*256)+D)*8/65535 or ((C*256)+D)/8192 |
| 01 | 25 | 4 | O2S2_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 26 | 4 | O2S3_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 27 | 4 | O2S4_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 28 | 4 | O2S5_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 29 | 4 | O2S6_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 2A | 4 | O2S7_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 2B | 4 | O2S8_WR_lambda(1): Equivalence Ratio Voltage | 0 0 | 2 8 | N/A V | ((A*256)+B)*2/65535 ((C*256)+D)*8/65535 |
| 01 | 2C | 1 | Commanded EGR | 0 | 100 | % | A*100/255 |
| 01 | 2D | 1 | EGR Error | -100 | 99.22 | % | (A-128) * 100/128 |
| 01 | 2E | 1 | Commanded evaporative purge | 0 | 100 | % | A*100/255 |
| 01 | 2F | 1 | Fuel Level Input | 0 | 100 | % | A*100/255 |
| 01 | 30 | 1 | # of warm-ups since codes cleared | 0 | 255 | N/A | A |
| 01 | 31 | 2 | Distance traveled since codes cleared | 0 | 65,535 | km | (A*256)+B |
| 01 | 32 | 2 | Evap. System Vapor Pressure | -8,192 | 8,192 | Pa | ((A*256)+B)/4 (A and B are two's complement signed) |
| 01 | 33 | 1 | Barometric pressure | 0 | 255 | kPa (Absolute) | A |
| 01 | 34 | 4 | O2S1_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 1.999 127.99 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 35 | 4 | O2S2_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 36 | 4 | O2S3_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32768 ((C*256)+D)/256 - 128 |
| 01 | 37 | 4 | O2S4_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 38 | 4 | O2S5_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 39 | 4 | O2S6_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 3A | 4 | O2S7_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 3B | 4 | O2S8_WR_lambda(1): Equivalence Ratio Current | 0 -128 | 2 128 | N/A mA | ((A*256)+B)/32,768 ((C*256)+D)/256 - 128 |
| 01 | 3C | 2 | Catalyst Temperature Bank 1, Sensor 1 | -40 | 6,513.5 | °C | ((A*256)+B)/10 - 40 |
| 01 | 3D | 2 | Catalyst Temperature Bank 2, Sensor 1 | -40 | 6,513.5 | °C | ((A*256)+B)/10 - 40 |
| 01 | 3E | 2 | Catalyst Temperature Bank 1, Sensor 2 | -40 | 6,513.5 | °C | ((A*256)+B)/10 - 40 |
| 01 | 3F | 2 | Catalyst Temperature Bank 2, Sensor 2 | -40 | 6,513.5 | °C | ((A*256)+B)/10 - 40 |
| 01 | 40 | 4 | PIDs supported [41 - 60] | Bit encoded [A7..D0] == [PID $41..PID $60] See below. | |||
| 01 | 41 | 4 | Monitor status this drive cycle | Bit encoded. See below. | |||
| 01 | 42 | 2 | Control module voltage | 0 | 65.535 | V | ((A*256)+B)/1000 |
| 01 | 43 | 2 | Absolute load value | 0 | 25,700 | % | ((A*256)+B)*100/255 |
| 01 | 44 | 2 | Command equivalence ratio | 0 | 2 | N/A | ((A*256)+B)/32768 |
| 01 | 45 | 1 | Relative throttle position | 0 | 100 | % | A*100/255 |
| 01 | 46 | 1 | Ambient air temperature | -40 | 215 | °C | A-40 |
| 01 | 47 | 1 | Absolute throttle position B | 0 | 100 | % | A*100/255 |
| 01 | 48 | 1 | Absolute throttle position C | 0 | 100 | % | A*100/255 |
| 01 | 49 | 1 | Accelerator pedal position D | 0 | 100 | % | A*100/255 |
| 01 | 4A | 1 | Accelerator pedal position E | 0 | 100 | % | A*100/255 |
| 01 | 4B | 1 | Accelerator pedal position F | 0 | 100 | % | A*100/255 |
| 01 | 4C | 1 | Commanded throttle actuator | 0 | 100 | % | A*100/255 |
| 01 | 4D | 2 | Time run with MIL on | 0 | 65,535 | minutes | (A*256)+B |
| 01 | 4E | 2 | Time since trouble codes cleared | 0 | 65,535 | minutes | (A*256)+B |
| 01 | 4F | 4 | Maximum value for equivalence ratio, oxygen sensor voltage, oxygen sensor current, and intake manifold absolute pressure | 0, 0, 0, 0 | 255, 255, 255, 2550 | , V, mA, kPa | A, B, C, D*10 |
| 01 | 50 | 4 | Maximum value for air flow rate from mass air flow sensor | 0 | 2550 | g/s | A*10, B, C, and D are reserved for future use |
| 01 | 51 | 1 | Fuel Type | From fuel type table see below | |||
| 01 | 52 | 1 | Ethanol fuel % | 0 | 100 | % | A*100/255 |
| 01 | 53 | 2 | Absolute Evap system Vapor Pressure | 0 | 327.675 | kPa | ((A*256)+B)/200 |
| 01 | 54 | 2 | Evap system vapor pressure | -32,767 | 32,768 | Pa | ((A*256)+B)-32767 |
| 01 | 55 | 2 | Short term secondary oxygen sensor trim bank 1 and bank 3 | -100 | 99.22 | % | (A-128)*100/128 (B-128)*100/128 |
| 01 | 56 | 2 | Long term secondary oxygen sensor trim bank 1 and bank 3 | -100 | 99.22 | % | (A-128)*100/128 (B-128)*100/128 |
| 01 | 57 | 2 | Short term secondary oxygen sensor trim bank 2 and bank 4 | -100 | 99.22 | % | (A-128)*100/128 (B-128)*100/128 |
| 01 | 58 | 2 | Long term secondary oxygen sensor trim bank 2 and bank 4 | -100 | 99.22 | % | (A-128)*100/128 (B-128)*100/128 |
| 01 | 59 | 2 | Fuel rail pressure (absolute) | 0 | 655,350 | kPa | ((A*256)+B) * 10 |
| 01 | 5A | 1 | Relative accelerator pedal position | 0 | 100 | % | A*100/255 |
| 01 | 5B | 1 | Hybrid battery pack remaining life | 0 | 100 | % | A*100/255 |
| 01 | 5C | 1 | Engine oil temperature | -40 | 210 | °C | A - 40 |
| 01 | 5D | 2 | Fuel injection timing | -210.00 | 301.992 | ° | (((A*256)+B)-26,880)/128 |
| 01 | 5E | 2 | Engine fuel rate | 0 | 3212.75 | L/h | ((A*256)+B)*0.05 |
| 01 | 5F | 1 | Emission requirements to which vehicle is designed | Bit Encoded | |||
| 01 | 60 | 4 | PIDs supported [61 - 80] | Bit encoded [A7..D0] == [PID $61..PID $80] See below. | |||
| 01 | 61 | 1 | Driver's demand engine - percent torque | -125 | 125 | % | A-125 |
| 01 | 62 | 1 | Actual engine - percent torque | -125 | 125 | % | A-125 |
| 01 | 63 | 2 | Engine reference torque | 0 | 65,535 | Nm | A*256+B |
| 01 | 64 | 5 | Engine percent torque data | -125 | 125 | % | A-125 Idle B-125 Engine point 1 C-125 Engine point 2 D-125 Engine point 3 E-125 Engine point 4 |
| 01 | 65 | 2 | Auxiliary input / output supported | Bit Encoded | |||
| 01 | 66 | 5 | Mass air flow sensor | ||||
| 01 | 67 | 3 | Engine coolant temperature | ||||
| 01 | 68 | 7 | Intake air temperature sensor | ||||
| 01 | 69 | 7 | Commanded EGR and EGR Error | ||||
| 01 | 6A | 5 | Commanded Diesel intake air flow control and relative intake air flow position | ||||
| 01 | 6B | 5 | Exhaust gas recirculation temperature | ||||
| 01 | 6C | 5 | Commanded throttle actuator control and relative throttle position | ||||
| 01 | 6D | 6 | Fuel pressure control system | ||||
| 01 | 6E | 5 | Injection pressure control system | ||||
| 01 | 6F | 3 | Turbocharger compressor inlet pressure | ||||
| 01 | 70 | 9 | Boost pressure control | ||||
| 01 | 71 | 5 | Variable Geometry turbo (VGT) control | ||||
| 01 | 72 | 5 | Wastegate control | ||||
| 01 | 73 | 5 | Exhaust pressure | ||||
| 01 | 74 | 5 | Turbocharger RPM | ||||
| 01 | 75 | 7 | Turbocharger temperature | ||||
| 01 | 76 | 7 | Turbocharger temperature | ||||
| 01 | 77 | 5 | Charge air cooler temperature (CACT) | ||||
| 01 | 78 | 9 | Exhaust Gas temperature (EGT) Bank 1 | Special PID. See below. | |||
| 01 | 79 | 9 | Exhaust Gas temperature (EGT) Bank 2 | Special PID. See below. | |||
| 01 | 7A | 7 | Diesel particulate filter (DPF) | ||||
| 01 | 7B | 7 | Diesel particulate filter (DPF) | ||||
| 01 | 7C | 9 | Diesel Particulate filter (DPF) temperature | ||||
| 01 | 7D | 1 | NOx NTE control area status | ||||
| 01 | 7E | 1 | PM NTE control area status | ||||
| 01 | 7F | 13 | Engine run time | ||||
| 01 | 80 | 4 | PIDs supported [81 - A0] | Bit encoded [A7..D0] == [PID $81..PID $A0] See below. | |||
| 01 | 81 | 21 | Engine run time for Auxiliary Emissions Control Device(AECD) | ||||
| 01 | 82 | 21 | Engine run time for Auxiliary Emissions Control Device(AECD) | ||||
| 01 | 83 | 5 | NOx sensor | ||||
| 01 | 84 | Manifold surface temperature | |||||
| 01 | 85 | NOx reagent system | |||||
| 01 | 86 | Particulate matter (PM) sensor | |||||
| 01 | 87 | Intake manifold absolute pressure | |||||
| 01 | A0 | 4 | PIDs supported [A1 - C0] | Bit encoded [A7..D0] == [PID $A1..PID $C0] See below. | |||
| 01 | C0 | 4 | PIDs supported [C1 - E0] | Bit encoded [A7..D0] == [PID $C1..PID $E0] See below. | |||
| 01 | C3 | ? | ? | ? | ? | ? | Returns numerous data, including Drive Condition ID and Engine Speed* |
| 01 | C4 | ? | ? | ? | ? | ? | B5 is Engine Idle Request B6 is Engine Stop Request* |
| 02 | 02 | 2 | Freeze frame trouble code | BCD encoded, See below. | |||
| 03 | N/A | n*6 | Request trouble codes | 3 codes per message frame, BCD encoded. See below. | |||
| 04 | N/A | 0 | Clear trouble codes / Malfunction indicator lamp (MIL) / Check engine light | Clears all stored trouble codes and turns the MIL off. | |||
| 05 | 0100 | OBD Monitor IDs supported ($01 – $20) | |||||
| 05 | 0101 | O2 Sensor Monitor Bank 1 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0102 | O2 Sensor Monitor Bank 1 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0103 | O2 Sensor Monitor Bank 1 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0104 | O2 Sensor Monitor Bank 1 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0105 | O2 Sensor Monitor Bank 2 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0106 | O2 Sensor Monitor Bank 2 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0107 | O2 Sensor Monitor Bank 2 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0108 | O2 Sensor Monitor Bank 2 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0109 | O2 Sensor Monitor Bank 3 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010A | O2 Sensor Monitor Bank 3 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010B | O2 Sensor Monitor Bank 3 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010C | O2 Sensor Monitor Bank 3 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010D | O2 Sensor Monitor Bank 4 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010E | O2 Sensor Monitor Bank 4 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 010F | O2 Sensor Monitor Bank 4 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0110 | O2 Sensor Monitor Bank 4 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Rich to lean sensor threshold voltage | |
| 05 | 0201 | O2 Sensor Monitor Bank 1 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0202 | O2 Sensor Monitor Bank 1 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0203 | O2 Sensor Monitor Bank 1 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0204 | O2 Sensor Monitor Bank 1 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0205 | O2 Sensor Monitor Bank 2 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0206 | O2 Sensor Monitor Bank 2 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0207 | O2 Sensor Monitor Bank 2 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0208 | O2 Sensor Monitor Bank 2 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0209 | O2 Sensor Monitor Bank 3 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020A | O2 Sensor Monitor Bank 3 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020B | O2 Sensor Monitor Bank 3 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020C | O2 Sensor Monitor Bank 3 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020D | O2 Sensor Monitor Bank 4 Sensor 1 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020E | O2 Sensor Monitor Bank 4 Sensor 2 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 020F | O2 Sensor Monitor Bank 4 Sensor 3 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 05 | 0210 | O2 Sensor Monitor Bank 4 Sensor 4 | 0.00 | 1.275 | Volts | 0.005 Lean to Rich sensor threshold voltage | |
| 09 | 00 | 4 | mode 9 supported PIDs 01 to 20 | Bit encoded | |||
| 09 | 01 | 1x5 | VIN Message Count in command 09 02 | Returns 1 line/packet (49 01 05 00 00 00 00), where 05 means 05 packets will be returned in VIN digits. | |||
| 09 | 02 | 5x5 | Vehicle identification number (VIN) | Returns the VIN as a multi-frame response using the ISO 15765-2 protocol. This is typically five frames, with the first frame encoding the size and count. | |||
| 09 | 04 | varies | calibration ID | Returns multiple lines, ASCII coded | |||
| 09 | 06 | 4 | calibration |
In the formula column, letters A, B, C, etc. represent the decimal equivalent of the first, second, third, etc. bytes of data. Where a (?) appears, contradictory or incomplete information was available. Someone with a copy of the 2006 SAE HS-3000 should fact-check these.
Bitwise encoded PIDs
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:
Mode 1 PID 00: A request for this PID returns 4 bytes of data. The four bytes are giving information about which of the next 32 PIDs are supported. The response can be decoded like this: If the car response is BE 1F A8 13, then transform that in binary.
B E 1 F A 8 1 3
---- ---- ---- ---- ---- ---- ---- ----------
supported? 1011 1110 0001 1111 1010 1000 0001 0 0 1 1
PID num 1234 5678 9ABC DEF. .... .... .... 1D 1E 1F 20
ex. 0101, 0103, 0104, 0105, 0106, 0107, 010C, 010D, 010E, 010F .... .... .... 011E, 011F
0 = not supported
1 = supported
Mode 1 PID 01: A request for this PID returns 4 bytes of data.
The first two bytes are identical for both spark ignition (Gasoline) and compression ignition (Diesel) engines. The third and fourth bytes are to be interpreted differently depending on if the engine is spark ignition or compression ignition. In the second (B) byte, bit 3 tells you which way to interpret the C and D bytes, with 0 being spark and 1 (set) being compression.
The first byte contains two pieces of information. Bit A7 (the eighth bit of byte A, the first byte) indicates whether or not the MIL (check engine light) is illuminated. Bits A0 through A6 represent the number of diagnostic trouble codes currently flagged in the ECU. The second, third, and fourth bytes give information about the availability and completeness of certain on-board tests. Note that test availability signified by set (1) bit; completeness signified by reset (0) bit:
| Bit | Name | Definition |
|---|---|---|
| A0-A6 | DTC_CNT | Number of confirmed emissions-related DTCs available for display. |
| A7 | MIL | Off or On, indicates if the CEL/MIL is on (or should be on) |
| B3 | NO NAME | 0 = Spark ignition monitors supported 1 = Compression ignition monitors supported |
| B7 | RESERVED | RESERVED |
Here are the common bit B definitions, they're test based.
Test available Test incomplete Misfire B0 B4 Fuel System B1 B5 Components B2 B6
The byte C and D spark ignition monitors:
Test available Test incomplete Catalyst C0 D0 Heated Catalyst C1 D1 Evaporative System C2 D2 Secondary Air System C3 D3 A/C Refrigerant C4 D4 Oxygen Sensor C5 D5 Oxygen Sensor Heater C6 D6 EGR System C7 D7
And the byte C and D compression ignition monitors:
Test available Test incomplete NMHC Cat C0 D0 NOx/SCR Monitor C1 D1 Boost Pressure C3 D3 Exhaust Gas Sensor C5 D5 PM filter monitoring C6 D6 EGR and/or VVT System C7 D7
NMHC *may* stand for non-methane hydrocarbons catalyst, but J1979 does not enlighten us.
Mode 1 PID 03: A request for this PID returns 2 bytes of data. The first byte describes fuel system #1. Only one bit should ever be set.
A0 Open loop due to insufficient engine temperature A1 Closed loop, using oxygen sensor feedback to determine fuel mix A2 Open loop due to engine load OR fuel cut due to deceleration A3 Open loop due to system failure A4 Closed loop, using at least one oxygen sensor but there is a fault in the feedback system A5-A7 Always zero
The second byte describes fuel system #2 (if it exists) and is encoded identically to the first byte.
Mode 1 PID 12: A request for this PID returns a single byte of data which describes the secondary air status. Only one bit should ever be set.
A0 Upstream of catalytic converter A1 Downstream of catalytic converter A2 From the outside atmosphere or off A3-A7 Always zero
Mode 1 PID 1C: A request for this PID returns a single byte of data which describes which OBD standards this ECU was designed to comply with. The hexadecimal and binary representations of the data byte are shown below next to what it implies:
$01 00000001b OBD-II as defined by the CARB $02 00000010b OBD as defined by the EPA $03 00000011b OBD and OBD-II $04 00000100b OBD-I $05 00000101b Not meant to comply with any OBD standard $06 00000110b EOBD (Europe) $07 00000111b EOBD and OBD-II $08 00001000b EOBD and OBD $09 00001001b EOBD, OBD and OBD II $0A 00001010b JOBD (Japan) $0B 00001011b JOBD and OBD II $0C 00001100b JOBD and EOBD $0D 00001101b JOBD, EOBD, and OBD II
Mode 1 PID 41: A request for this PID returns 4 bytes of data. The first byte is always zero. The second, third, and fourth bytes give information about the availability and completeness of certain on-board tests. Note that test availability signified by set (1) bit; completeness signified by reset (0) bit:
Test enabled Test incomplete Misfire B0 B4 Fuel System B1 B5 Components B2 B6 Reserved B3 B7 Catalyst C0 D0 Heated Catalyst C1 D1 Evaporative System C2 D2 Secondary Air System C3 D3 A/C Refrigerant C4 D4 Oxygen Sensor C5 D5 Oxygen Sensor Heater C6 D6 EGR System C7 D7
Mode 3: (no PID required) A request for this mode 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 DTC's (4 bytes) 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. The text description of a trouble code may be decoded as follows. The first character in the trouble code is determined by the first two bits in the first byte:
A7 A6 First DTC character -- -- ------------------- 0 0 P - Powertrain 0 1 C - Chassis 1 0 B - Body 1 1 U - Network
The four following digits are BCD encoded.
The second character in the DTC is a number defined by
A5 A4 Second DTC character -- -- -------------------- 0 0 0 0 1 1 1 0 2 1 1 3
The third character in the DTC is a number defined by
A3 A2 A1 A0 Third DTC character -- -- -- -- ------------------- 0 0 0 0 0 0 0 0 1 1 0 0 1 0 2 0 0 1 1 3 0 1 0 0 4 0 1 0 1 5 0 1 1 0 6 0 1 1 1 7 1 0 0 0 8 1 0 0 1 9 1 0 1 0 A 1 0 1 1 B 1 1 0 0 C 1 1 0 1 D 1 1 1 0 E 1 1 1 1 F
The fourth and fifth characters are defined in the same way as the third, but using bits B7..B4 and B3..B0. The resulting five-character code should look something like "U0158" and can be looked up in a table of OBD-II DTCs. Hexadecimal characters (0-9,A-F), while relatively rare, are allowed in the last 3 positions of the code itself.
Fuel Type Coding
Mode 1 PID $51 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
01 Gasoline 02 Methanol 03 Ethanol 04 Diesel 05 LPG 06 CNG 07 Propane 08 Electric 09 Bifuel running Gasoline 0A Bifuel running Methanol 0B Bifuel running Ethanol 0C Bifuel running LPG 0D Bifuel running CNG 0E Bifuel running Prop 0F Bifuel running Electricity 10 Bifuel mixed gas/electric 11 Hybrid gasoline 12 Hybrid Ethanol 13 Hybrid Diesel 14 Hybrid Electric 15 Hybrid Mixed fuel 16 Hybrid Regenerative
Special PIDs
Some PIDs are to be interpreted specially, and aren't necessarily exactly "bitwise encoded"
Mode 1 PID 78
A request for this PID will return 9 bytes of data. The first byte is a bit encoded field indicating which sensors are supported:
Sensor Supported EGT11 A0 EGT12 A1 EGT13 A2 EGT14 A3 Reserved A4 Reserved A5 Reserved A6 Reserved A7
The remaining bytes are 16 bit integers indicating the temperature in Degrees celsius in the range -40 to 6513.5 (scale 0.1) using the usual ((A*256)+B)-40 formula.
Mode 1 PID 79
A request for this PID will return 9 bytes of data. See Mode 1 PID 78 (above) for a description.
Non-standard PIDs
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 starts from US $7500
However, even ETI membership will not provide full documentation for non-standard PIDs. ETI state
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 of today's per year charges as we know them: GM $50,000 Honda $5,000 Suzuki $1,000 BMW $7,000 plus $1,000 per update. Updates occur every quarter. (This is more now, but do not have exact number)
CAN (11-bit) Bus format
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 $7DF, which acts as a broadcast address, and accepts responses from any ID in the range $7E8 to $7EF. ECUs that can respond to OBD queries listen both to the functional broadcast ID of $7DF and one assigned ID in the range $7E0 to $7E7. Their response has an ID of their assigned ID plus 8 e.g. $7E8 through $7EF.
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 $7DF.
CAN bus may also be used for communication beyond the standard OBD messages. Physical addressing uses particular CAN IDs for specific modules (e.g., 720 for the instrument cluster in Fords) with proprietary frame payloads.
Query
The functional PID query is sent to the vehicle on the CAN bus at ID 7DFh, using 8 data bytes. The bytes are:
| Byte -> | _ 0 _ | _ 1 _ | _ 2 _ | _ 3 _ | _ 4 _ | _ 5 _ | _ 6 _ | _ 7 _ |
|---|---|---|---|---|---|---|---|---|
| SAE Standard | Number of additional data bytes: 2 | Mode 01 = show current data; 02 = freeze frame; etc. | PID code (e.g.: 05 = Engine coolant temperature) | not used (may be 55h) | ||||
| Vehicle specific | Number of additional data bytes: 3 | Custom mode: (e.g.: 22 = enhanced data) | PID code (e.g.: 4980h) | not used (may be 00h or 55h) | ||||
Response
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. The bytes are:
| Byte -> | _ 0 _ | _ 1 _ | _ 2 _ | _ 3 _ | _ 4 _ | _ 5 _ | _ 6 _ | _ 7 _ |
|---|---|---|---|---|---|---|---|---|
| SAE Standard 7E8h, 7E9h, 7EAh, etc. | Number of additional data bytes: 3 to 6 | Custom mode Same as query, except that 40h is added to the mode 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 mode: same as query, except that 40h is added to the mode value.(e.g.: 62h = response to mode 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 mode: (e.g.: 22h = enhanced diagnostic data by PID, 21h = enhanced data by offset) | 31h | not used (may be 00h) | |||
