P0900
Clutch Actuator Circuit/Open
The TCM detects an open circuit at the clutch actuator output. Used on automated manual or dual-clutch transmissions.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: shop_only
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.
- Actuator winding openCommon
- Wiring breakPossible
- Pin pushed back out of connector bodyLess likely
Parts involved
- Clutch Actuator
- Wiring Harness
- TCM
P0900 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.