P0B66
Hybrid/EV Battery Voltage Sense I Circuit High
The BMS detects a circuit high fault on voltage sense channel I of the high-voltage battery. Cell-group voltage measurement is unreliable on this channel.
- 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.
- Sense wire shorted to higher voltageCommon
- Reference regulator overvoltagePossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Hv Battery Voltage Sense I
- Wiring Harness
- Bms
P0B66 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.