Fault codes
Fault codes, and what's actually behind each one
What the code actually means on your car — not the definition every scanner prints, and not the part someone already quoted you for.
101F01Air mass system, plausibility: calculated air masses not plausible
The engine computer's calculated intake air mass does not match what is measured. For the N55, BMW's own dealer bulletin says re-adapt first after programming or a battery reset, then smoke-test the intake and crankcase ventilation before any part, and not replace the DME.
29CDMisfire, cylinder 1
Cylinder 1 misfire — the code names the cylinder, not the cause. On the N54 it can be a coil, a plug, an injector, or low fuel pressure from the high-pressure pump.
29F1Fuel high-pressure, plausibility
The engine computer's high-pressure fuel reading does not add up — a high-pressure-side plausibility code that BMW's N54 bulletin lists beside 29F2, 2FBF and 29DC.
29F2Fuel high-pressure, fuel pressure undershot
High-pressure fuel below target on the N54 — one of the codes in BMW's high-pressure pump bulletin, stored with 29DC and 2FBF when the car loses power.
2A82VANOS intake – stiff; jammed mechanically
The intake camshaft did not reach its VANOS target in time. BMW's own bulletin for the N51, N52 and N54 points at oil supply to the solenoids first, not at the camshaft hardware.
2A87VANOS exhaust – stiff; jammed mechanically
The exhaust camshaft missed its VANOS target — the exhaust-side twin of 2A82, from the same BMW bulletin, with the same first suspects: oil supply and the solenoids.
2DEDPower management: closed-circuit current violation
The engine computer flagged the parked car's current draw as above its limit. In the threads read, the causes owners found ranged from a plugged-in or constant-power accessory to a door lock actuator keeping the footwell module awake, and in one case a failing water pump and thermostat.
2E7CBSD bus communication fault
The engine computer lost communication on the BSD bus, which the threads list as running to the alternator, electric water pump, oil condition sensor and battery sensor. The one confirmed ending in the threads read is corrosion on the engine computer connector pins.
2E81Electric coolant pump, speed deviation, speed outside tolerance
The electric water pump is running outside its speed tolerance. Usually the pump; sometimes its power or ground — and the thermostat beside it is part of the same job.
30FFDME: Turbocharger, charge-air pressure too low
The engine computer measured less boost than it asked for. On the twin-turbo N54 the cause can sit anywhere in boost control — vacuum supply, hoses, the two control solenoids, the wastegate actuators, or the wastegate valves inside the turbos.
387FPower management: standby current violation
The standby current limit was exceeded while the car sat. In the threads read it came after a tuning adapter or module was added, plus a few cases with no clear cause.
6EC4Steering angle sensor: steering angle only relative, center position unknown (learned quadrant active, turn to end position)
The steering angle sensor has lost its center reference and is waiting to relearn it. One E90 owner cleared it with a lock-to-lock turn after a forum reply; the other reply was a scan-tool calibration or an alignment-shop centring.
801C20Central gateway (ZGM): central fault memory full, no control unit fault
The central gateway's own fault memory is full. In the threads read it is an overflow notice rather than a failed module, and one reply says it will not stay cleared while the faults behind it remain.
8041B6Headlight range control (LWR): system failed
The headlight levelling system reports failure, with a headlight vertical aim message in the cluster. The threads read show it with a failing levelling (TMS) module, after a headlight conversion, and on a car where a dealer quoted a whole headlight but the owner then found the harness to a ride-height sensor cut.
93C3Seat occupancy detector
The front passenger seat-occupancy mat is not reading properly, so the airbag and seat belt lights come on, often only when someone sits there. While the light is on the passenger airbag can be deactivated. BMW recalled the mat on some 2006 E60/E61 and sport-seat E90/E91 cars.
A0B4CAS: Engine start, starter operation
The CAS sent the start command and the start did not happen. A no-crank code from the access system — not a steering-lock code.
A559Instrument cluster: power supply has been switched off (closed-circuit current cutoff relay)
The cluster supply, terminal 30g-f, was switched off by the car. One E90 owner had it stored with only a lift indicator light and no other fault; the one repair vendor that lists causes puts the battery first.
A6CFAUC sensor
A fault in the AUC, the automatic air-recirculation (air-quality) sensor, on E9x cars, per the threads and a code library. One repair-tips page says it is a transmission fault; none of the other sources agree.
C90D60AUC (automatic air recirculation control) sensor fault
The junction box stored a fault for the sensor behind automatic air recirculation. It is a comfort fault with no engine effect and not urgent; one owner cleared it by cleaning the sensor connector pins.
CD0487Central gateway (ZGW): synchronization process for FlexRay failed
The gateway stored that FlexRay synchronization failed. In the threads read it sits with no symptom on newer cars, and among wheel-speed, ICM and chassis faults on an older F30.
D904CAS: K-CAN line fault
The CAS reports a fault on the K-CAN body bus. Neither thread read reached a confirmed cause.