P2E78
Hybrid/EV Battery Pack Coolant Temperature Sensor D Circuit Intermittent/Erratic
The ECM detects a circuit intermittent/erratic fault on the hybrid/ev battery pack coolant temperature sensor d circuit. Reading cannot be used reliably for control.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
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.
- Sensor connector not seatedCommon
- Noisy ground referencePossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Hybrid Battery Coolant Temp Sensor D
- Wiring Harness
- Bms
P2E78 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.