What are OBD diagnostics?
The on-board diagnostics system “OBD” first saw service in the 2000s and therefore equips the majority of vehicles produced since that time. This tool allowing a more specific reading of error codes is connected to a socket called an “OBD port”, standing for On-Board Diagnostic.
How does OBD work?
The On-board Diagnostic, thanks to the various sensors that inform the on-board computer, detects fault codes. When they are present, these fault codes are shown to the vehicle’s user by a display on the dashboard called an MIL (Malfunction Indicator Lamp).
To be able to translate these fault codes and translate them into human terms, a diagnostic pack is used: this is a digital tool on which are stored all possible fault codes for a vehicle according to its options, year of build, engine type, as well as the various technologies it uses.
How do you decrypt a fault code?
The first letter indicates the fault code family:
- P: Powertrain, namely the engine and the gearbox
- C: Chassis
- B: Bodywork
- U: Network
The first digit indicates whether the code is generic or not (green digit):
- 0: General issue
- 1: Manufacturer-specific issue
The three last digits correspond with:
- 0, 1 and 2: to check the air/fuel mix
- 3: for the ignition system
- 4: to check for auxiliary emissions
- 5: to check engine idling
Source : http://www.outilsobdfacile.fr/