What does code P1548 mean?

Q: What does code P1548 mean?

A/C Recirculation Circuit. P1548 on GM vehicles indicates that the powertrain control module (PCM) has detected an abnormal condition in the air conditioning (A/C) recirculation circuit, which controls the blend door that switches between fresh outside air and recirculated cabin air. The PCM monitors the circuit for expected voltage or resistance and sets the code when the signal falls outside the programmed range, often due to a faulty actuator, wiring issue, or door binding.

DTC codes / GM codes / P1548

P1548 · GMA/C Recirculation Circuit

P1548 on GM vehicles indicates that the powertrain control module (PCM) has detected an abnormal condition in the air conditioning (A/C) recirculation circuit, which controls the blend door that switches between fresh outside air and recirculated cabin air. The PCM monitors the circuit for expected voltage or resistance and sets the code when the signal falls outside the programmed range, often due to a faulty actuator, wiring issue, or door binding.

SystemPowertrain

Code typeGM specific

SeverityLow

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

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