P2B29
Hybrid/EV Battery Pack Coolant Pump A Overspeed - Dry Run
The hybrid control module detects that battery pack coolant pump A is running above the calibrated maximum speed without load. Indicates dry running due to coolant loss or air ingestion.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
Common causes
Ordered by how often each turns out to be the cause.
- Coolant loss in battery loopCommon
- Air drawn into pump suctionPossible
- Pack cell imbalance approaching service thresholdLess likely
Parts involved
- Hybrid Battery Coolant Pump A
- Battery Pack Coolant Loop
P2B29 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.