Does your car have a fault code? Here is what it means.
Standard fault codes, or diagnostic trouble codes (DTCs), are a common language across car makes: Peugeot, Renault, Volkswagen, Audi, BMW and more. A compatible car diagnostic scanner can read and interpret them. Enter your code to go straight to its definition.
How do you read a code?
Tap a character to see what it means.
Fault category
The letter tells you which part of the car is affected.
- PPowertrain: engine and transmission
- CChassis: brakes, suspension and steering
- BBody: airbags, seats and lighting
- UNetwork communication between control units
Code origin
Generic or manufacturer-specific.
- 0Generic fault: the same across all makes. These are the codes listed here.
- 1Manufacturer-specific fault: added by Peugeot, Renault, VW and others when the generic list is not sufficient.
The system involved
Applies to P-series codes.
- 0-2Fuel and air metering
- 3Ignition system
- 4Auxiliary emission controls
- 5Idle speed control
- 6Computer and auxiliary outputs
- 7-9Transmission control
- A-CHybrid propulsion
The fault identifier
Identifies the specific fault; some identifiers use hexadecimal characters.
- 01Here, "01" identifies cylinder 1: P0301 = cylinder 1 misfire detected.
- 0-FCharacters can run from 0 to 9 and A to F (hexadecimal numbering).
The first letter: which part of the car?
A code always starts with a letter, which tells you where to look in the car. P codes, covering the engine and transmission, account for the vast majority of warning light issues.
Powertrain
Engine and transmission. By far the most common category: fuel injection, ignition, exhaust and transmission systems.
Chassis
Brakes, ABS, suspension and power steering: the systems that keep the car under control.
Body
Interior and equipment: airbags, seat belts, windows, lighting and comfort systems.
Network communication
Communication between the car's control units. A fault here can trigger several warning lights at once.
The 3rd character: the affected system
For P-series codes, this character identifies a group of systems. It gives you an initial clue before you read the full definition.
The 2nd character identifies the code's origin: 0 for a generic code shared across makes (the codes listed here), or 1 for a manufacturer-specific code. The last three characters identify the fault, sometimes using hexadecimal characters (0-9 and A-F).
These codes are standardised in SAE J2012 and ISO 15031-6.
Browse the definitions by range
Here are definitions of the most common fault codes. Choose the range containing your code or open the complete list. All 11,000 definitions are included in our EOBD Facile car diagnostic software. It is free and lets you read fault codes using an ELM327-compatible adapter or an ELM323 adapter.
Select the fault code range
A warning light is on, but you cannot see a code?
Connect a klavkarr scanner to your car's OBD port. In 30 seconds, the EOBD Facile app displays your fault codes explained in English, with all 11,000 built-in definitions, not just those on this page.
No subscription, free updates and a 2-year warranty.
What you see on screen
P0301
Cylinder 1 Misfire Detected - More details...
P0420
Catalyst System Efficiency Below Threshold (Bank 1) - More details...
P0000
No Fault Codes Detected
Frequently asked questions about fault codes
Where can I see my car's fault code?
A dashboard warning light alone does not show the code, which is stored in a control unit. Read it with a diagnostic scanner connected to the OBD port, usually under the dashboard on the driver's side.
My code is not listed. Is that a problem?
Not necessarily. This page covers the most common generic codes. Codes starting with P1, C, B or U, and more specific codes, are covered by the 11,000 definitions in our EOBD Facile software.
Can I clear a fault code myself?
Yes, with a klavkarr scanner and the EOBD Facile app. Remember: clearing a code does not repair the fault. If the cause remains, the warning light will return. Permanent codes cannot be cleared manually: the vehicle clears them after repairs when the relevant on-board checks confirm that the fault is no longer present.
Is a fault code enough to repair the car?
It gives you a starting point, not a complete diagnosis. P0130 (oxygen sensor circuit) may be caused by the sensor itself, its wiring or an air leak. Our guides explain which checks to make for each code before replacing a part.