P2B28
Hybrid/EV Battery Pack Coolant Pump A Performance
The hybrid control module detects that battery pack coolant pump A does not produce the expected flow for the commanded duty. Battery thermal management may be impaired.
- 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.
- Pump output degraded with ageCommon
- Air pocket in coolant loopPossible
- Pack cell imbalance approaching service thresholdLess likely
Parts involved
- Hybrid Battery Coolant Pump A
- Battery Pack
- Hybrid Control Module
P2B28 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.