120308
High120308 — Insufficient Boost Pressure
Description
What the Code Means
Code 120308 indicates insufficient boost pressure. The DME (engine control unit) monitors boost pressure via the MAP (Manifold Absolute Pressure) sensor and sets the fault when actual pressure deviates from the target value. Causes can include a faulty turbocharger or supercharger, low engine oil pressure, EGR system faults, or air leaks in the intake tract.
Symptoms
Symptoms
- Loss of engine power
- Reduced acceleration
- Check Engine light comes on
- Car goes into limp mode
Causes and fixes
Diagnosis and Repair
- Check for boost leaks — run a smoke test on the intake tract.
- Inspect the turbocharger — check wastegate and actuator operation.
- Test the boost pressure sensor — verify MAP sensor readings.
- Check the EGR valve — make sure it isn't sticking.
- Check oil supply to the turbo — verify pressure and that the oil passage is clean.
Possible secondary damage
Secondary Damage
Prolonged operation with insufficient boost can damage the turbocharger through oil starvation or overspeeding. The catalytic converter can also fail from running on a rich mixture.