P25E9 code meaning
Supercharger Disconnect Clutch Stuck Open
Powertrain system Generic code P25xx codes Check engine light
What P25E9 means
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.
P25E9 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1.5 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P25E9
- Check engine lamp on
- Weak acceleration from low engine speed
- Normal pull once the turbocharger takes over
Common causes of P25E9
- Most 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
- Less likelyAccessory drive belt slipping or damaged at the supercharger pulley
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Supercharger clutchClutch solenoidClutch pulley
What each part of P25E9 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. |
| E9 | The exact fault in that area. |
What to do next
- Note P25E9 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 P25E9
What does P25E9 mean?
P25E9 means "Supercharger Disconnect Clutch Stuck Open". Some engines drive their mechanical supercharger through an electromagnetic clutch, so the blower only turns when extra low-speed torque is wanted. It is a generic code, so it means the same on every make.
Is it safe to drive with P25E9?
Drive gently and only to a workshop. With P25E9 the car can go into limp mode (reduced power) to protect itself.
Will P25E9 fail an emissions test?
Yes, it can. P25E9 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 P25E9 to fix?
Difficulty: hard. A typical repair takes 1.5 to 6 hours of work. This is a job for a workshop.
Will P25E9 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.