P25B4 code meaning
Turbocharger/Supercharger Wastegate A Stuck Closed
Powertrain system Generic code P25xx codes Check engine light
What P25B4 means
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.
P25B4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P25B4
- Power reduced because the module limits boost
- Possible overboost code alongside
- Check engine lamp on
Common causes of P25B4
- Most 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)
- Less likelyInternal turbocharger fault requiring replacement (Ford SSM 50670)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wastegate aTurbocharger a
What each part of P25B4 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| B4 | The exact fault in that area. |
What to do next
- Note P25B4 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P25B4
What does P25B4 mean?
P25B4 means "Turbocharger/Supercharger Wastegate A Stuck Closed". P25B4 is the reverse of P25B3: the module asked wastegate A to open, yet the valve stays shut or opens far too little. It is a generic code, so it means the same on every make.
Is it safe to drive with P25B4?
Drive gently and only to a workshop. With P25B4 the car can go into limp mode (reduced power) to protect itself.
Will P25B4 fail an emissions test?
Yes, it can. P25B4 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P25B4 to fix?
Difficulty: hard. A typical repair takes 0.5 to 8 hours of work. This is a job for a workshop.
Will P25B4 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.