OBD-II code · Powertrain (generic, extended)
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.
Is it safe to drive with P25B4?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyCarbon-locked wastegate flap
- PossibleSeized linkage
- Less likelyCarbon or debris buildup preventing free movement
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1.5–6 h
- Emissions test
- Likely to fail
- Parts involved
- Wastegate A, Turbocharger A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.