Powertrain
generic / SAE
P25B4
Turbocharger/Supercharger Wastegate A Stuck Closed
Wastegate A is mechanically stuck closed. The turbo cannot bleed off exhaust at high load — boost overshoots the setpoint, risking overboost cut-off and damage to the turbo bearing. Carbon-locked flap, seized linkage or aged actuator are typical causes.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / B4
Possible causes
- Carbon-locked wastegate flap high
- Seized linkage medium
- Carbon or debris buildup preventing free movement low
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 400–2500 €
- Estimated time: 1.5–6 h
- Component: wastegate a
- Component: turbocharger a
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012