Featured fault codes
These codes have full write-ups: severity, provenance, schematic cross-links and community repair opinions where recorded.
120308Charging pressure control: too low (B58)Turbo & charge air · Service soon29E0Mixture too leanFuel & air metering · Service soon29E1Fuel pressure sensor signalFuel & air metering · Stop / drive carefully29E2Fuel injection rail, pressure sensor signalFuel & air metering · Service soon2A82VANOS intake control faultOther · Service soon2A99VANOS exhaust: control fault, camshaft stuck (community list)VANOS / camshaft · Service soon30FFTurbocharger, charge-air pressure too low (underboost)Turbo & charge air · Service soonP0171System too lean (Bank 1)Powertrain · Service soonP0300Random/multiple cylinder misfire detectedPowertrain · Stop / drive carefullyP0301Cylinder 1 misfire detectedPowertrain · Stop / drive carefullyP0306Cylinder 6 misfire detectedPowertrain · Stop / drive carefullyP0420Catalyst system efficiency below threshold (Bank 1)Powertrain · Service soonU0100Lost communication with ECM/PCM 'A'Network · Stop / drive carefully
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N54N54 fault codesThe classic twin-turbo I6 trouble set.B58B58 fault codesModern straight-six charge-air and e-wastegate codes.
Every BMW code
The full catalogue — 211 hex codes from open community research plus the generic SAE J2012 set — is searchable in the known-codes browser. The DTC decoder resolves a single code on demand.
Fault-code questions
Why do BMW codes look different from OBD-II codes?
BMW uses 4-hex and 6-hex manufacturer codes alongside the generic SAE J2012 P/B/C/U codes. Both describe the same underlying faults, but the hex codes carry BMW-specific detail the generic set flattens.
Where do the descriptions come from?
Open community research (BimmerFest, Bimmerforums, SpoolStreet, BimmerProfs and others) plus the public-domain SAE definitions. No proprietary ISTA text is reproduced.