P0AA5
Hybrid/EV Battery Negative Contactor Circuit Stuck Open
The HV battery negative contactor is stuck open. HV system cannot establish a complete circuit.
- 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.
- Contactor mechanically failedCommon
- Contactor coil burnt outPossible
- Carbon or debris buildup preventing free movementLess likely
Parts involved
- Hv Battery Negative Contactor
- Bms
P0AA5 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.