OBD-II code · Powertrain (generic, extended)
P28C4 Clutch A Phase U-V-W Circuit Low
The output stage for the clutch A BLDC motor reports a low phase voltage on at least one of the U/V/W phases. Short to ground or interrupted half-bridge.
Is it safe to drive with P28C4?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyPhase wire shorted to ground
- PossibleLow-side switch open in driver
- Less likelyConnector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 3–10 h
- Emissions test
- Usually unaffected
- Parts involved
- Clutch Motor A, Wiring Harness, Tcm
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.