Diagnostic Database

OBD-II CODE LOOKUP

Search 17,000+ fault codes — every P, B, C, and U code with real causes, diagnostic steps, and repair guidance. The most complete free OBD-II database online.

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P
Powertrain
Engine, transmission, fuel system, and emissions codes. The most common category in daily diagnostics.
P0001–P3999 · 12,000+ codes
B
Body
Airbag/SRS, HVAC, power windows, locks, lighting systems, and body electronics.
B0001–B3999 · 2,500+ codes
C
Chassis
ABS, traction control, ESC, steering, suspension, and other chassis system codes.
C0001–C3999 · 1,800+ codes
U
Network / Bus
CAN bus communication faults, module communication errors, and network failure codes.
U0001–U3999 · 800+ codes
P0300 MISFIRE ◆ P0420 CATALYST ◆ P0171 LEAN BANK 1 ◆ P0455 EVAP LARGE LEAK ◆ P0700 TRANS CONTROL ◆ P0401 EGR FLOW ◆ P0128 THERMOSTAT ◆ P0507 IDLE HIGH ◆ P0340 CAM SENSOR ◆ C0035 ABS SENSOR ◆ U0100 CAN BUS ◆ B0001 AIRBAG ◆ P0300 MISFIRE ◆ P0420 CATALYST ◆ P0171 LEAN BANK 1 ◆ P0455 EVAP LARGE LEAK ◆ P0700 TRANS CONTROL ◆ P0401 EGR FLOW ◆ P0128 THERMOSTAT ◆ P0507 IDLE HIGH ◆ P0340 CAM SENSOR ◆ C0035 ABS SENSOR ◆ U0100 CAN BUS ◆ B0001 AIRBAG ◆