2C57

What the Code Means

Code 2C57 is a plausibility fault in the boost pressure control system. The DME compares actual boost pressure against the calculated target and logs a mismatch: actual pressure is lower than expected. This behavior is typical of a faulty turbocharger diverter (cut-off) valve with a weak spring, vacuum leaks, or a faulty wastegate actuator — part of the airflow or the control signal is lost, and the turbo never reaches its commanded boost level.

Severity is moderate: the engine stays drivable, but you lose pulling power.

Symptoms

• Check Engine Light comes on.
• Lack of power, sluggish acceleration.
• Intermittent loss of boost.
• Overall drop in engine performance.

Diagnosis and Repair

Work from the most likely cause to the least likely.

1. Replace the turbocharger diverter (cut-off) valve — the most common cause, especially a valve with a weak spring. The OEM part number depends on the specific engine; match it by VIN.
2. Check the vacuum lines to the wastegate for leaks: cracks, loose clamps, and loss of sealing lead to incomplete wastegate control.
3. Check the wastegate actuator — the rod should move correctly and hold its position.
4. Inspect the turbocharger for mechanical faults if the previous steps turn up nothing.

Secondary Issues

• Higher exhaust gas temperatures during prolonged operation with low boost.
• Potential catalytic converter damage.
• Lower fuel economy.

Don't put off the repair: these consequences develop during extended driving with the fault present.