P26D8
Engine Coolant Pump Clutch Stuck On
The coolant pump clutch remains engaged when commanded off. Pump runs continuously, slowing warm-up and increasing parasitic load.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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.
- Armature plate seized to the pulley faceCommon
- Driver stuck on keeps clutch energisedPossible
- Carbon or debris buildup preventing free movementLess likely
Parts involved
- Coolant Pump Clutch
P26D8 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.