P0E72
Hybrid/EV Battery Internal Isolation Performance
The BMS detects degraded internal isolation between HV bus and battery enclosure. Insulation resistance below safety threshold.
- 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.
- Internal cell insulation agedCommon
- Internal moisturePossible
- Pack cell imbalance approaching service thresholdLess likely
Parts involved
- Hv Battery Pack
- Bms
- Isolation Monitor
P0E72 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.