Two technicians are diagnosing a poorly running engine with no stored DTCs. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates the PCM is defective. Who is right?

Question

Quizplus · Accepted Answer

When the MAF (Mass Air Flow) sensor is unplugged and the engine runs better, it typically indicates that the MAF sensor is providing incorrect air flow information to the PCM (Powertrain Control Module), supporting Technician A's statement. There is no direct indication that the PCM itself is defective based on this symptom alone, making Technician B's diagnosis less likely.

Two Technicians Are Diagnosing a Poorly Running Engine with No