From Wikipedia, the free encyclopedia
OBD-II PIDs ( Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool.
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
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 , 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
Typically, an
will use PIDs with a
connected to the vehicle's OBD-II connector.
The technician enters the PID
The scan tool sends it to the vehicle's
(CAN)-bus, VPW, PWM, ISO, . (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
There are ten modes of operation described in the latest OBD-II standard SAE J1979. They are as follows:
Mode (hex)
Description
Show current data
Show freeze frame data
Show stored Diagnostic Trouble Codes
Clear Diagnostic Trouble Codes and stored values
Test results, oxygen sensor monitoring (non CAN only)
Test results, other component/system monitoring (Test results, oxygen sensor monitoring for CAN only)
Show pending Diagnostic Trouble Codes (detected during current or last driving cycle)
Control operation of on-board component/system
Request vehicle information
(DTCs) (Cleared DTCs)
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
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
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.
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.
Data bytes returned
Description
PIDs supported [01 - 20]
Bit encoded [A7..D0] == [PID $01..PID $20]
Monitor status since DTCs cleared. (Includes malfunction indicator lamp (MIL) status and number of DTCs.)
Bit encoded.
Freeze DTC
Fuel system status
Bit encoded.
Calculated engine load value
Engine coolant temperature
Short term fuel % trim—Bank 1
-100 Subtracting Fuel (Rich Condition)
99.22 Adding Fuel (Lean Condition)
(A-128) * 100/128
Long term fuel % trim—Bank 1
-100 Subtracting Fuel (Rich Condition)
99.22 Adding Fuel (Lean Condition)
(A-128) * 100/128
Short term fuel % trim—Bank 2
-100 Subtracting Fuel (Rich Condition)
99.22 Adding Fuel (Lean Condition)
(A-128) * 100/128
Long term fuel % trim—Bank 2
-100 Subtracting Fuel (Rich Condition)
99.22 Adding Fuel (Lean Condition)
(A-128) * 100/128
Fuel pressure
kPa (gauge)
Intake manifold absolute pressure
kPa (absolute)
Engine RPM
((A*256)+B)/4
Vehicle speed
Timing advance
° relative to #1 cylinder
Intake air temperature
MAF air flow rate
((A*256)+B) / 100
Throttle position
Commanded secondary air status
Bit encoded.
Oxygen sensors present
[A0..A3] == Bank 1, Sensors 1-4. [A4..A7] == Bank 2...
Bank 1, Sensor 1:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 1, Sensor 2:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 1, Sensor 3:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 1, Sensor 4:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 2, Sensor 1:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 2, Sensor 2:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 2, Sensor 3:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
Bank 2, Sensor 4:
Oxygen sensor voltage,
Short term fuel trim
-100(lean)
99.2(rich)
(B-128) * 100/128 (if B==$FF, sensor is not used in trim calc)
OBD standards this vehicle conforms to
Bit encoded.
Oxygen sensors present
Similar to PID 13, but [A0..A7] == [B1S1, B1S2, B2S1, B2S2, B3S1, B3S2, B4S1, B4S2]
Auxiliary input status
A0 == Power Take Off (PTO) status (1 == active)
[A1..A7] not used
Run time since engine start
PIDs supported [21 - 40]
Bit encoded [A7..D0] == [PID $21..PID $40]
Distance traveled with malfunction indicator lamp (MIL) on
Fuel Rail Pressure (relative to manifold vacuum)
((A*256)+B) * 0.079
Fuel Rail Pressure (diesel, or gasoline direct inject)
kPa (gauge)
((A*256)+B) * 10
O2S1_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535 or ((A*256)+B)/32768
((C*256)+D)*8/65535 or ((C*256)+D)/8192
O2S2_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S3_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S4_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S5_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S6_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S7_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
O2S8_WR_lambda(1):
Equivalence Ratio
((A*256)+B)*2/65535
((C*256)+D)*8/65535
(A-128) * 100/128
Commanded evaporative purge
Fuel Level Input
# of warm-ups since codes cleared
Distance traveled since codes cleared
Evap. System Vapor Pressure
((A*256)+B)/4 (A and B are
Barometric pressure
kPa (Absolute)
O2S1_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S2_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S3_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32768
((C*256)+D)/256 - 128
O2S4_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S5_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S6_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S7_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
O2S8_WR_lambda(1):
Equivalence Ratio
((A*256)+B)/32,768
((C*256)+D)/256 - 128
Catalyst Temperature
Bank 1, Sensor 1
((A*256)+B)/10 - 40
Catalyst Temperature
Bank 2, Sensor 1
((A*256)+B)/10 - 40
Catalyst Temperature
Bank 1, Sensor 2
((A*256)+B)/10 - 40
Catalyst Temperature
Bank 2, Sensor 2
((A*256)+B)/10 - 40
PIDs supported [41 - 60]
Bit encoded [A7..D0] == [PID $41..PID $60]
Monitor status this drive cycle
Bit encoded.
Control module voltage
((A*256)+B)/1000
Absolute load value
((A*256)+B)*100/255
Fuel/Air commanded equivalence ratio
((A*256)+B)/32768
Relative throttle position
Ambient air temperature
Absolute throttle position B
Absolute throttle position C
Accelerator pedal position D
Accelerator pedal position E
Accelerator pedal position F
Commanded throttle actuator
Time run with MIL on
Time since trouble codes cleared
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
Maximum value for air flow rate from mass air flow sensor
A*10, B, C, and D are reserved for future use
From fuel type table
Ethanol fuel %
Absolute Evap system Vapor Pressure
((A*256)+B)/200
Evap system vapor pressure
((A*256)+B)-32767
Short term secondary oxygen sensor trim bank 1 and bank 3
(A-128)*100/128
(B-128)*100/128
Long term secondary oxygen sensor trim bank 1 and bank 3
(A-128)*100/128
(B-128)*100/128
Short term secondary oxygen sensor trim bank 2 and bank 4
(A-128)*100/128
(B-128)*100/128
Long term secondary oxygen sensor trim bank 2 and bank 4
(A-128)*100/128
(B-128)*100/128
Fuel rail pressure (absolute)
((A*256)+B) * 10
Relative accelerator pedal position
Hybrid battery pack remaining life
Engine oil temperature
Fuel injection timing
(((A*256)+B)-26,880)/128
Engine fuel rate
((A*256)+B)*0.05
Emission requirements to which vehicle is designed
Bit Encoded
PIDs supported [61 - 80]
Bit encoded [A7..D0] == [PID $61..PID $80]
Driver's demand engine - percent torque
Actual engine - percent torque
Engine reference torque
Engine percent torque data
A-125 Idle
B-125 Engine point 1
C-125 Engine point 2
D-125 Engine point 3
E-125 Engine point 4
Auxiliary input / output supported
Bit Encoded
Mass air flow sensor
Engine coolant temperature
Intake air temperature sensor
Commanded EGR and EGR Error
Commanded Diesel intake air flow control and relative intake air flow position
Exhaust gas recirculation temperature
Commanded throttle actuator control and relative throttle position
Fuel pressure control system
Injection pressure control system
Turbocharger compressor inlet pressure
Boost pressure control
Variable Geometry turbo (VGT) control
Wastegate control
Exhaust pressure
Turbocharger RPM
Turbocharger temperature
Turbocharger temperature
Charge air cooler temperature (CACT)
Exhaust Gas temperature (EGT) Bank 1
Special PID.
Exhaust Gas temperature (EGT) Bank 2
Special PID.
Diesel particulate filter (DPF)
Diesel particulate filter (DPF)
Diesel Particulate filter (DPF) temperature
NOx NTE control area status
PM NTE control area status
Engine run time
PIDs supported [81 - A0]
Bit encoded [A7..D0] == [PID $81..PID $A0]
Engine run time for Auxiliary Emissions Control Device(AECD)
Engine run time for Auxiliary Emissions Control Device(AECD)
NOx sensor
Manifold surface temperature
NOx reagent system
Particulate matter (PM) sensor
Intake manifold absolute pressure
PIDs supported [A1 - C0]
Bit encoded [A7..D0] == [PID $A1..PID $C0]
PIDs supported [C1 - E0]
Bit encoded [A7..D0] == [PID $C1..PID $E0]
Returns numerous data, including Drive Condition ID and Engine Speed*
B5 is Engine Idle Request
B6 is Engine Stop Request*
Data bytes returned
Description
Mode 02 accepts the same PIDs as mode 01, with the same meaning, but information given is from when the freeze frame was created.
You have to send the frame number in the data section of the message.
Data bytes returned
Description
DTC that caused freeze frame to be stored.
BCD encoded.
Data bytes returned
Description
Request trouble codes
3 codes per message frame.
Data bytes returned
Description
Clear trouble codes / Malfunction indicator lamp (MIL) / Check engine light
Clears all stored trouble codes and turns the MIL off.
Data bytes returned
Description
OBD Monitor IDs supported ($01 – $20)
O2 Sensor Monitor Bank 1 Sensor 1
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 2
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 3
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 4
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 1
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 2
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 3
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 4
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 1
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 2
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 3
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 4
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 1
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 2
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 3
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 4
0.005 Rich to lean sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 1
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 2
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 3
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 1 Sensor 4
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 1
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 2
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 3
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 2 Sensor 4
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 1
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 2
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 3
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 3 Sensor 4
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 1
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 2
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 3
0.005 Lean to Rich sensor threshold voltage
O2 Sensor Monitor Bank 4 Sensor 4
0.005 Lean to Rich sensor threshold voltage
Data bytes returned
Description
Data bytes returned
Description
Mode 9 supported PIDs (01 to 20)
Bit encoded. [A7..D0] = [PID $01..PID $20]
VIN Message Count in PID 02. Only for ISO 9141-2, ISO 14230-4 and SAE J1850.
Usually value will be 5.
17-char VIN, ASCII-encoded and left-padded with null chars (0x00) if needed to.
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).
Calibration ID
Up to 16 ASCII chars. Data bytes not used will be reported as null bytes (0x00).
Calibration verification numbers (CVN) message count for PID 06. Only for ISO 9141-2, ISO 14230-4 and SAE J1850.
Calibration Verification Numbers (CVN)
Raw data left-padded with null characters (0x00). Usually displayed as hex string.
In-use performance tracking message count for PID 08 and 0B. Only for ISO 9141-2, ISO 14230-4 and SAE J1850.
8 if sixteen (16) values are required to be reported, 9 if eighteen (18) values are required to be reported, and 10 if twenty (20) values are required to be reported (one message reports two values, each one consisting in two bytes).
In-use performance tracking for spark ignition vehicles
4 or 5 messages, each one containing 4 bytes (two values).
ECU name message count for PID 0A
ASCII-coded. Right-padded with null chars (0x00).
In-use performance tracking for compression ignition vehicles
5 messages, each one containing 4 bytes (two values).
Data bytes returned
Description
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.
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:
A request for this PID returns 4 bytes of data. Each bit, from
to , represents one of the next 32 PIDs and is giving information about if it is supported.
For example, if the car response is BE1FA813, it can be decoded like this:
Hexadecimal
Supported?
PID number
So, supported PIDs are: 01, 03, 04, 05, 06, 07, 0C, 0D, 0E, 0F, 10, 11, 13, 15, 1C, 1F and 20
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 ( of byte A, the first byte) indicates whether or not the MIL (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. Note that test availability is indicated by set (1) bit and completeness is indicated by reset (0) bit.
Definition
Off or On, indicates if the CEL/MIL is on (or should be on)
Number of confirmed emissions-related DTCs available for display.
Reserved (should be 0)
0 = Spark ignition monitors supported
1 = Compression ignition monitors supported
Here are the common bit B definitions, they are test based.
Test available
Test incomplete
Fuel System
Components
The third and fourth bytes are to be interpreted differently depending on if the engine is
or . In the second (B) byte, bit 3 indicates how to interpret the C and D bytes, with 0 being spark and 1 (set) being compression.
The bytes C and D for spark ignition monitors:
Test available
Test incomplete
Heated Catalyst
Evaporative System
Secondary Air System
A/C Refrigerant
Oxygen Sensor
Oxygen Sensor Heater
EGR System
And the bytes C and D for compression ignition monitors:
Test available
Test incomplete
NMHC Catalyst
NOx/SCR Monitor
Boost Pressure
Exhaust Gas Sensor
PM filter monitoring
EGR and/or VVT System
NMHC may stand for Non-Methane HydroCarbons, but J1979 does not enlighten us.
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 is represented by a set (1) bit and completeness is represented by a reset (0) bit:
Test enabled
Test incomplete
Components
Fuel System
EGR System
Oxygen Sensor Heater
Oxygen Sensor
A/C Refrigerant
Secondary Air System
Evaporative System
Heated Catalyst
A request for this PID will return 9 bytes of data. The first byte is a bit encoded field indicating which
sensors are supported:
Description
Supported EGT sensors
Temperature read by EGT11
Temperature read by EGT12
Temperature read by EGT13
Temperature read by EGT14
The first byte is bit-encoded as follows:
Description
EGT bank 1, sensor 4 Supported?
EGT bank 1, sensor 3 Supported?
EGT bank 1, sensor 2 Supported?
EGT bank 1, sensor 1 Supported?
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
formula (MSB is A, LSB is B). Only values for which the corresponding sensor is supported are meaningful.
The same structure applies to PID 79, but values are for sensors of bank 2.
A request for this mode returns a list of the DTCs that have been set. The list is encapsulated using the
If there are two or fewer DTCs (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:
First DTC character
P - Powertrain
C - Chassis
U - Network
The two following digits are encoded as 2 bits. The second character in the DTC is a number defined by the following table:
Second DTC character
The third character in the DTC is a number defined by
Third DTC character
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.
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.
All data items of the In-use Performance Tracking record consist of two (2) bytes and are reported in this order (each message contains two items, hence the message length is 4):
Description
OBD Monitoring Conditions Encountered Counts
Ignition Counter
Catalyst Monitor Completion Counts Bank 1
Catalyst Monitor Conditions Encountered Counts Bank 1
Catalyst Monitor Completion Counts Bank 2
Catalyst Monitor Conditions Encountered Counts Bank 2
O2 Sensor Monitor Completion Counts Bank 1
O2 Sensor Monitor Conditions Encountered Counts Bank 1
O2 Sensor Monitor Completion Counts Bank 2
O2 Sensor Monitor Conditions Encountered Counts Bank 2
EGR Monitor Completion Condition Counts
EGR Monitor Conditions Encountered Counts
AIR Monitor Completion Condition Counts (Secondary Air)
AIR Monitor Conditions Encountered Counts (Secondary Air)
EVAP Monitor Completion Condition Counts
EVAP Monitor Conditions Encountered Counts
Secondary O2 Sensor Monitor Completion Counts Bank 1
Secondary O2 Sensor Monitor Conditions Encountered Counts Bank 1
Secondary O2 Sensor Monitor Completion Counts Bank 2
Secondary O2 Sensor Monitor Conditions Encountered Counts Bank 2
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 (2) bytes and are reported in this order (each message contains two items, hence message length is 4):
Description
OBD Monitoring Conditions Encountered Counts
Ignition Counter
NMHC Catalyst Monitor Completion Condition Counts
NMHC Catalyst Monitor Conditions Encountered Counts
NOx/SCR Catalyst Monitor Completion Condition Counts
NOx/SCR Catalyst Monitor Conditions Encountered Counts
NOx Adsorber Monitor Completion Condition Counts
NOx Adsorber Monitor Conditions Encountered Counts
PM Filter Monitor Completion Condition Counts
PM Filter Monitor Conditions Encountered Counts
Exhaust Gas Sensor Monitor Completion Condition Counts
Exhaust Gas Sensor Monitor Conditions Encountered Counts
EGR and/or VVT Monitor Completion Condition Counts
EGR and/or VVT Monitor Conditions Encountered Counts
Boost Pressure Monitor Completion Condition Counts
Boost Pressure Monitor Conditions Encountered Counts
Fuel Monitor Completion Condition Counts
Fuel Monitor Conditions Encountered Counts
Some PIDs are to be interpreted specially, and aren't necessarily exactly bitwise encoded, or in any scale. The values for these PIDs are .
A request for this PID returns 2 bytes of data. The first byte describes fuel system #1.
Description
Open loop due to insufficient engine temperature
Closed loop, using oxygen sensor feedback to determine fuel mix
Open loop due to engine load OR fuel cut due to deceleration
Open loop due to system failure
Closed loop, using at least one oxygen sensor but there is a fault in the feedback system
Any other value is an invalid response. There can only be one bit set at most.
The second byte describes fuel system #2 (if it exists) and is encoded identically to the first byte.
A request for this PID returns a single byte of data which describes the secondary air status.
Description
Downstream of catalytic converter
From the outside atmosphere or off
Pump commanded on for diagnostics
Any other value is an invalid response. There can only be one bit set at most.
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:
Description
OBD-II as defined by the
OBD as defined by the
OBD and OBD-II
Not OBD compliant
EOBD (Europe)
EOBD and OBD-II
EOBD and OBD
EOBD, OBD and OBD II
JOBD (Japan)
JOBD and OBD II
JOBD and EOBD
JOBD, EOBD, and OBD II
Engine Manufacturer Diagnostics (EMD)
Engine Manufacturer Diagnostics Enhanced (EMD+)
Heavy Duty On-Board Diagnostics (Child/Partial) (HD OBD-C)
Heavy Duty On-Board Diagnostics (HD OBD)
World Wide Harmonized OBD (WWH OBD)
Heavy Duty Euro OBD Stage I without NOx control (HD EOBD-I)
Heavy Duty Euro OBD Stage I with NOx control (HD EOBD-I N)
Heavy Duty Euro OBD Stage II without NOx control (HD EOBD-II)
Heavy Duty Euro OBD Stage II with NOx control (HD EOBD-II N)
Brazil OBD Phase 1 (OBDBr-1)
Brazil OBD Phase 2 (OBDBr-2)
Korean OBD (KOBD)
India OBD I (IOBD I)
India OBD II (IOBD II)
Heavy Duty Euro OBD Stage VI (HD EOBD-IV)
Not available for assignment (SAE
special meaning)
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 the following table:
Description
Not available
running Gasoline
Bifuel running Methanol
Bifuel running Ethanol
Bifuel running LPG
Bifuel running CNG
Bifuel running Propane
Bifuel running Electricity
Bifuel running electric and combustion engine
Hybrid gasoline
Hybrid Ethanol
Hybrid Diesel
Hybrid Electric
Hybrid running electric and combustion engine
Hybrid Regenerative
Bifuel running diesel
Any other value is reserved by ISO/SAE. There are currently no definitions for .
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
and only available to members. The price of ETI membership for access to scan codes starts from US$7,500.
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 $17,500 plus $1,000 per update. Updates occur every quarter. (This is more now, but do not have exact number)
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.
The functional PID query is sent to the vehicle on the CAN bus at ID 7DFh, using 8 data bytes. The bytes are:
SAE Standard
additional
data bytes:
(e.g.: 05 = Engine coolant temperature)
(may be 55h)
Vehicle specific
additional
data bytes:
Custom mode: (e.g.: 22 = enhanced data)
(e.g.: 4980h)
(may be 00h or 55h)
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 ( protocol form Frameformat with 8 data bytes). The bytes are:
SAE Standard
additional
data bytes:
Custom mode
Same as query, except that 40h is added to the mode value. So:
(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)
(may be 00h or 55h)
Vehicle specific
7E8h, or 8h + physical ID of module.
additional
data bytes:
Custom mode: same as query, except that 40h is added to the mode value.(e.g.: 62h = response to mode 22h request)
(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.
additional
data bytes:
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)
(may be 00h)
. Electric Auto Association - Plug in Hybrid Electric Vehicle 2013.
2013. showing cost of access to OBD-II PID documentation
, including manufacturer-specific codes.
, description and repair information for most makes of vehicles.
Partial list of
vehicles which support the OBD-II CAN bus standard.
Sample fault code data read using the OBDKey Bluetooth, OBDKey USB and OBDKey WLAN vehicle interface units.
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