P28C5Clutch A Motor Phase U-V-W Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- With P28C5 the controller finds one or more phases of the clutch A motor sitting higher than the switching pattern allows, as if a lead were tied to battery voltage. The motor in question is the brushless drive of an on-demand pump actuator: Getrag introduced this concept with the 7DCT300, where one motor per clutch turns a gerotor pump and the pump pressure itself closes the clutch. Causes on the high side are a phase touching a supply wire in the harness, moisture bridging pins in the connector, or an output transistor that no longer switches off. Unlike P28C4 the fault points away from ground. Thresholds are not published by any manufacturer. The transmission typically drops clutch A and runs on the remaining shaft.
- What you may notice
- Warning lamp for the transmission and stored DTC
- Half of the gear set unavailable, vehicle continues with reduced choice
- Clutch A may not open or close on command
- Likely causes
- LikelyMotor phase lead shorted to a supply line in the harness
- PossibleMoisture or corrosion bridging pins at the actuator connector
- RareHigh-side switch in the controller that no longer turns off
- 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 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.