OBD fault code library

Look up any P or U code to see what it means, what causes it, the parts involved and how it gets fixed.

Free on OBD DashX

Looking for real-world repair data?

OBD DashX shows which problems come with each code, how often they show up in other vehicles, and how to fix them — step by step.

  • Real-world fix data
  • How often it happens
  • Step-by-step repairs
Browse codes on OBD DashX No sign-up needed · available in 10 languages

Fault codes

P1977 Issue in secondary air injection valve (controls emission)
Audi Auxiliary Emissions Control High severity
P1978 Issue in secondary air injection valve (controls emission)
Audi Auxiliary Emissions Control High severity
P1979 Issue in secondary air injection valve (controls emission)
Audi Auxiliary Emissions Control High severity
P1980 Issue in secondary air injection valve (controls emission)
Audi Auxiliary Emissions Control High severity
P1981 Issue in secondary air injection valve (controls emission)
Audi Auxiliary Emissions Control High severity
P1982 Issue in exhaust gas temperature sensor
Audi Auxiliary Emissions Control High severity
P1983 Issue in exhaust gas temperature sensor
Audi Auxiliary Emissions Control High severity
P1984 Issue in radiator fan
Audi Fuel and Air Metering High severity
P1985 Issue in engine coolant fan
Audi Fuel and Air Metering High severity
P1986 Short circuit detected in engine coolant control module
Audi Computer Output Circuit High severity
P1987 Issue in brake temperature sensor
Audi Vehicle Speed and Idle Control System High severity
P1988 Issue in exhaust cooling system
Audi Auxiliary Emissions Control High severity
P1989 Issue in exhaust cooling system
Audi Auxiliary Emissions Control High severity
P1990 Issue in exhaust cooling system
Audi Auxiliary Emissions Control High severity
P1991 Internal malfunction detected in ECM
Audi Computer Output Circuit High severity

Search fault codes

Scan your own car

Read and clear fault codes, live data and service resets with the CaRPM app.