With P25FA the control line of bypass valve C carries more voltage than the engine module expects for the commanded state. A wire shorted to battery voltage is the classic reason; on a ground-switched valve an open coil or broken lead also lets the line float up to supply level. A short to voltage can make the driver stage overheat and cut out, so the valve is no longer operated at all. On an electric recirculation valve, the effect is that it no longer opens on throttle lift-off and the compressor can surge, with the typical fluttering sound and some stress on the charger. No manufacturer documents P25FA for valve C; GM-based Saab engines monitor the same fault for valve A as part of a continuous type B circuit check. The low-side fault is P25F9.
Medium severity. Can I keep driving?Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
Symptoms
- Check engine lamp on
- Fluttering or surging noise when lifting off the throttle
Most likely causes
- Control wire shorted to battery voltage
- Open valve coil on a ground-switched circuit
- Damaged output stage in the engine control module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P25FA means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 5: Speed and idle
- FA: Specific fault in that system
Frequently asked questions
Can I keep driving with code P25FA?
Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
What causes code P25FA?
The most common causes are: control wire shorted to battery voltage; open valve coil on a ground-switched circuit; damaged output stage in the engine control module.
Related codes
- P25F8Turbocharger/Supercharger Bypass Valve C Control Circuit
- P25F9Turbocharger/Supercharger Bypass Valve C Control Circuit Low
- P25FBTurbocharger/Supercharger Bypass Valve C Control Circuit Range/Performance
- P0035Turbocharger/Supercharger Bypass Valve A Control Circuit High
- P00C2Turbocharger/Supercharger Bypass Valve B Control Circuit High
Sources
- law.cornell.edu: 13 CCR 1968.2
- saabwisonline.com: dtc p0033 p0035
- ms-motorservice.com: electric recirculating air valves
- en.wikipedia.org: Blowoff valve
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.