OBD-II code · Powertrain (generic)
P0B77 Hybrid/EV Battery Voltage Sense M Circuit
The BMS detects a circuit fault on voltage sense channel M of the high-voltage battery. Cell-group voltage measurement is unreliable on this channel.
Is it safe to drive with P0B77?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelySense circuit failed
- PossibleWiring fault
- Less likelyPack cell imbalance approaching service threshold
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–8 h
- Emissions test
- Usually unaffected
- Parts involved
- Hv Battery Voltage Sense M, Wiring Harness, Bms
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- P0B95Hybrid/EV Battery Voltage Sense S Circuit
- P0B74Hybrid/EV Battery Voltage Sense L Circuit Low
- P0B75Hybrid/EV Battery Voltage Sense L Circuit High
- P0B76Hybrid/EV Battery Voltage Sense L Circuit Intermittent/Erratic
- P0B78Hybrid/EV Battery Voltage Sense M Circuit Range/Performance
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- P0B7AHybrid/EV Battery Voltage Sense M Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.