P2DE8
Cold Start Engine Coolant Bypass Valve D Stuck Open
During cold start, the engine coolant bypass valve D is stuck in the open position. Coolant bypasses the warm-up loop.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Valve stuck in open positionCommon
- Actuator failedPossible
- Carbon or debris buildup preventing free movementLess likely
Parts involved
- Engine Coolant Bypass Valve D
P2DE8 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.