OBD-II code · Powertrain (generic)
P0C78 Hybrid/EV Battery System Precharge Time Too Long
The HV battery system precharge time is longer than the calibrated window. Indicates high resistance, weak contactor, or aged components.
Is it safe to drive with P0C78?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyIncreased resistance in path
- PossibleContactor coil weakening
- 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
- 2–10 h
- Emissions test
- Usually unaffected
- Parts involved
- Hv Battery System, Precharge Resistor, Main Contactors
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.