P25E9Supercharger Disconnect Clutch Stuck Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some engines drive their mechanical supercharger through an electromagnetic clutch, so the blower only turns when extra low-speed torque is wanted. Eaton's TVS blower on the T6 Drive-E four-cylinder from Volvo is built this way, where the turbocharger takes over at higher revs. P25E9 means the engine computer has asked for the clutch to engage, but the supercharger is not being driven – the clutch stays open or slips, so no blower boost arrives. How the fault is recognised (blower speed, pressure rise) is not published. No manufacturer documents this code publicly; CARB treats supercharger electronics as monitored output components. The opposite failure is P25EA. Drivers notice a flat, hesitant pull-away until the turbo spools up.
- What you may notice
- Check engine lamp on
- Weak acceleration from low engine speed
- Normal pull once the turbocharger takes over
- Likely causes
- LikelyWorn friction faces or too large an air gap, so the clutch slips or will not pull in
- PossibleClutch coil with an internal fault producing too little magnetic force
- PossibleLow supply voltage or high resistance at the clutch connector
- RareAccessory drive belt slipping or damaged at the supercharger pulley
- 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: €300 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.