What does code P1257 mean?

Q: What does code P1257 mean?

Boost Control Fault / Supercharger Overboost. P1257 on a GM vehicle indicates that the powertrain control module (PCM) has detected an overboost condition in the supercharger or turbocharger system, meaning the manifold pressure exceeded the commanded limit for a calibrated time. The PCM monitors the boost control solenoid and the manifold absolute pressure (MAP) sensor to determine if the actual boost pressure is higher than the desired pressure, which can trigger this fault when the boost control system fails to regulate pressure properly.

DTC codes / GM codes / P1257

P1257 · GMBoost Control Fault / Supercharger Overboost

P1257 on a GM vehicle indicates that the powertrain control module (PCM) has detected an overboost condition in the supercharger or turbocharger system, meaning the manifold pressure exceeded the commanded limit for a calibrated time. The PCM monitors the boost control solenoid and the manifold absolute pressure (MAP) sensor to determine if the actual boost pressure is higher than the desired pressure, which can trigger this fault when the boost control system fails to regulate pressure properly.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

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