P28C5 code meaning
Clutch A Motor Phase U-V-W Circuit High
Powertrain system Generic code P28xx codes Check engine light
What P28C5 means
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.
P28C5 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28C5
- 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
Common causes of P28C5
- Most likelyMotor phase lead shorted to a supply line in the harness
- PossibleMoisture or corrosion bridging pins at the actuator connector
- Less likelyHigh-side switch in the controller that no longer turns off
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Clutch motor aWiring harnessTCM
What each part of P28C5 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| C5 | The exact fault in that area. |
What to do next
- Note P28C5 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P28C5
What does P28C5 mean?
P28C5 means "Clutch A Motor Phase U-V-W Circuit High". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P28C5?
Drive gently and only to a workshop. With P28C5 the car can go into limp mode (reduced power) to protect itself.
Will P28C5 fail an emissions test?
Yes, it can. P28C5 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P28C5 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P28C5 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.