Powertrain, generic (extended)

P25E9 Supercharger Disconnect Clutch Stuck Open

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Worn friction faces or too large an air gap, so the clutch slips or will not pull in
Clutch coil with an internal fault producing too little magnetic force
Low supply voltage or high resistance at the clutch connector
Accessory drive belt slipping or damaged at the supercharger pulley

Symptoms

  • Check engine lamp on
  • Weak acceleration from low engine speed
  • Normal pull once the turbocharger takes over

Repair estimate

DifficultyHardWorkshop job
Parts and labour€300–3,000
Time1.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

supercharger clutchclutch solenoidclutch pulley

Related codes

P25EAP25FEP25EBP0299P2263

References: law.cornell.edu, mobilityengineeringtech.com, en.wikipedia.org.