P28DAClutch B 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
- P28DA concerns the electrical circuit of the sensor that reports the rotor angle of the clutch B motor, and is chiefly stored when that signal disappears because a line is open. Electronic commutation of a brushless motor relies on this angle to energise U, V and W in the right order; it also lets the controller count revolutions and compare pump speed with the pressure sensor. Without a valid signal the clutch B pump is stopped and the gears on that shaft are no longer offered. Usual culprits are a broken sensor supply or ground, a pin pushed out of the connector, or a dead Hall or magnetic element inside the actuator. P28DB handles a signal that exists but is inconsistent; P28CB is the clutch A equivalent. Details are unpublished.
- What you may notice
- Clutch B out of service, half of the gears missing
- Transmission warning lamp on
- Motor speed codes for clutch B may be stored as follow-up faults
- Likely causes
- LikelyOpen supply, ground or signal line of the clutch B motor position sensor
- PossiblePin pushed out or bent at the clutch B actuator connector
- PossibleFailed sensing element inside the clutch B 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 – €1,300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.