P2CF8
Engine Coolant Bypass Valve D Control Circuit Driver Current/Temperature Too High
The output driver for the engine coolant bypass valve D actuator reports current or junction temperature above its protection threshold. Stalled actuator or short to ground.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- Check engine light on
- Cooling fan runs constantly or not at all
- Cabin heater weak or excessively hot
- Possible long warm-up time or hard cold start
Common causes
Ordered by how often each turns out to be the cause.
- Bypass actuator mechanically jammedCommon
- Control wire shorted to groundPossible
Parts involved
- Engine Coolant Bypass Valve D
- ECM
P2CF8 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.