OBD-II code · Powertrain (generic)
P0B78 Hybrid/EV Battery Voltage Sense M Circuit Range/Performance
The BMS detects a circuit range/performance 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 P0B78?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelySense voltage drifted
- PossibleHigh-resistance contact
- Less likelySensor element aged beyond calibration window
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
Related codes
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- P0B5FHybrid/EV Battery Voltage Sense H Circuit Range/Performance
- P0B64Hybrid/EV Battery Voltage Sense I Circuit Range/Performance
- P0B69Hybrid/EV Battery Voltage Sense J Circuit Range/Performance
- P0B6EHybrid/EV Battery Voltage Sense K Circuit Range/Performance
- P0B73Hybrid/EV Battery Voltage Sense L Circuit Range/Performance
- P0B7DHybrid/EV Battery Voltage Sense N Circuit Range/Performance
- P0B82Hybrid/EV Battery Voltage Sense O Circuit Range/Performance
- P0B87Hybrid/EV Battery Voltage Sense P Circuit Range/Performance
- P0B8CHybrid/EV Battery Voltage Sense Q Circuit Range/Performance
- P0B91Hybrid/EV Battery Voltage Sense R Circuit Range/Performance
- P0B96Hybrid/EV Battery Voltage Sense S Circuit Range/Performance
- P0B75Hybrid/EV Battery Voltage Sense L Circuit High
- P0B76Hybrid/EV Battery Voltage Sense L Circuit Intermittent/Erratic
- P0B77Hybrid/EV Battery Voltage Sense M Circuit
- P0B79Hybrid/EV Battery Voltage Sense M Circuit Low
- P0B7AHybrid/EV Battery Voltage Sense M Circuit High
- P0B7BHybrid/EV Battery Voltage Sense M Circuit Intermittent/Erratic
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.