Description of the standard trouble OBD codes by family
Standard or generic fault codes are a list of codes common to all manufacturers.
This list of faults, also called DTC (for Data Trouble Code) has been defined so that any diagnostic device can read and decode them. They have a standard format as shown below :
The first letter indicates the family of DTC.
- P: Powertrain, (i.e. engine and gearbox)
- C: Chassis
- B: Body
- U: User network
The first digit indicates if the code is generic or not (green digit):
- 0: Generic fault
- 1: Manufacturer fault
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As the list of generic OBD codes is not always sufficient, manufacturers can add as many of their own codes as they need.
The last 3 digits correspond to an incremented number (purple digits).
This may be a hexadecimal number (i.e. from 0 to 9 + from A to F). For P family codes, sub-families have been defined using the 1st digit (in this example the "3"):
- 0 , 1 and 2: for the air/fuel mixture
- 3 : for the ignition system
- 4 : for checking auxiliary emissions
- 5 : for engine idling
- 6 : for the onboard computer and ancillary outputs
- 7, 8 and 9: for the transmission (gearbox)
- A, B and C : for hybrid propulsion
These OBD codes were standardized using SAE J2012 and ISO 15031-6 standards which, to our knowledge, contain about 11 000 definitions in the most recent version.
Below you will find a list of the most commonly used codes. Our software contains all of the 11 000 codes. Don't hesitate to download it. It is free and, using an ELM327 or ELM323 interface, can be used to read the fault codes. For more details, go to our EOBD-Facile car diagnostic software page.