What does code P1174 mean?

Q: What does code P1174 mean?

Fuel Trim Adaptation Additive Bank 1 Malfunction. P1174 on BMW vehicles indicates that the engine control module has detected an additive fuel trim adaptation value on bank 1 that has exceeded its acceptable limit, meaning the base air-fuel mixture is consistently too lean or too rich at idle and low-load conditions. The additive trim is the idle-range correction, so the fault points to a vacuum leak, a faulty mass air flow sensor, or a fuel delivery issue that affects the engine mainly when it is idling.

DTC codes / BMW codes / P1174

P1174 · BMWFuel Trim Adaptation Additive Bank 1 Malfunction

P1174 on BMW vehicles indicates that the engine control module has detected an additive fuel trim adaptation value on bank 1 that has exceeded its acceptable limit, meaning the base air-fuel mixture is consistently too lean or too rich at idle and low-load conditions. The additive trim is the idle-range correction, so the fault points to a vacuum leak, a faulty mass air flow sensor, or a fuel delivery issue that affects the engine mainly when it is idling.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.