P2B85
Engine Coolant Pump Underspeed
The engine coolant pump runs below the calibrated minimum speed for the commanded duty. Mechanical resistance high or supply voltage low.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Mechanical load increased (binding)Common
- Supply voltage low under loadPossible
Parts involved
- Engine Coolant Pump
- ECM
P2B85 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.