P28C8
Clutch A Pump Motor Performance
The clutch A hydraulic pump motor does not produce the expected flow for the commanded speed. Worn pump, leakage, or aged motor characteristic.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Common causes
Ordered by how often each turns out to be the cause.
- Hydraulic pump wornCommon
- Motor characteristic agedPossible
Parts involved
- Clutch Motor A
- Clutch Actuator A
P28C8 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.