Code result
P0C78
Hybrid/EV Battery System Precharge Time Too Long
High severity
What it means
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?
No — stop driving
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.
Most likely causes
Increased resistance in path
highOne of the most commonly reported causes for this code — check this first.
Contactor coil weakening
mediumA plausible cause — test and verify before replacing parts.
Pack cell imbalance approaching service threshold
lowLess common, but worth ruling out after the more likely causes.
Related help
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