P28CBClutch A Motor Position Sensor Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- A brushless motor can only be commutated correctly if the electronics know where the rotor stands; P28CB reports that the signal from the sensor tracking the clutch A motor's rotor position is missing or electrically unusable, mostly through an open line. Without it the controller cannot switch the U-V-W phases in the right order or count motor revolutions, so the pump of clutch A is shut down. In Getrag-type pump actuators these brushless ferrite motors are shared parts, and the position signal also serves to check motor speed against the pressure target. Typical causes: an open sensor feed or ground, a corroded pin, a failed sensor element. P28CC covers a signal that is present but implausible. No manufacturer publishes P28CB details.
- What you may notice
- Clutch A disabled, gears on that shaft unavailable
- Transmission warning lamp
- Possibly also motor speed codes stored
- Likely causes
- LikelyOpen signal, supply or ground wire of the clutch A motor position sensor
- PossibleCorroded or loose pin at the actuator connector
- PossibleFailed position sensor inside the actuator
- 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: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.