P28C9Clutch A Motor Overspeed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P28C9 is stored when the clutch A motor turns faster than the controller considers plausible for the pressure it is asked to hold. Because the pump in such actuators delivers oil straight into the closed clutch circuit, the motor should slow down once pressure is reached; if it keeps racing, the oil is escaping or the pump is not loaded. Likely reasons are a leaking clutch piston seal, air drawn in at low fluid level, or a broken coupling between motor shaft and gerotor so that the motor spins free. A faulty rotor position signal can also fake a high speed, which is why P28CB/P28CC deserve a look first. P28CA is the opposite case. No carmaker publishes limits for P28C9.
- What you may notice
- Clutch A slips or fails to transmit full torque
- Transmission warning and restricted gear choice
- Likely causes
- LikelyOil escaping from the clutch A pressure circuit, e.g. worn piston seal
- PossiblePump drawing air because of low fluid level or clogged suction filter
- RareBroken drive between motor shaft and gerotor rotor
- RareFaulty motor position signal reporting too high a speed
- 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: €100 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.