P25B4Turbocharger/Supercharger Wastegate A Stuck Closed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P25B4 is the reverse of P25B3: the module asked wastegate A to open, yet the valve stays shut or opens far too little. Ford uses the same position comparison for both directions (error over 20 mm for 2.5 s); in 2024 it appears as P0243 with failure type 73. Other makers infer the fault from pressure. Porsche explains that its DME judges the wastegate by the boost building up ahead of the throttle; on the 2021 Cayenne E3 PHEV during catalyst warm-up (bulletin 2230) and on Cayenne E-Hybrid models after a dynamic engine start from electric driving (250/22), a weak build-up was misread as a jammed valve, cured by DME software. Audi did the same for the 2018–2019 RS 5. Ford SSM 50670 for 2.3 L EcoBoost Ranger, Bronco and Explorer built from 14 Dec 2021 says: clear, road test under load, and replace the turbo if P25B4 returns.
- What you may notice
- Power reduced because the module limits boost
- Possible overboost code alongside
- Check engine lamp on
- Likely causes
- LikelyWastegate flap or spindle seized shut by carbon or corrosion
- PossibleActuator or linkage unable to move the valve
- PossibleFalse detection by engine software (Porsche Cayenne, Audi RS 5)
- RareInternal turbocharger fault requiring replacement (Ford SSM 50670)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.