Battery management system (BMS) malfunction or precharge control fault. High-voltage battery cell imbalance that affects the precharge check. Battery temperature sensor fault or thermal data outside the expected range.

Record the exact DTC P1B77, dashboard message, state of charge, temperature, and whether it happened during startup or charging. Reduce driving speed and avoid long trips if the EV warning returns, READY mode is unstable, or charging is limited. Scan for companion BMS, contactor, ICCU, 12V, or high-voltage isolation codes before clearing anything.

Is it safe to drive with P1B77?

🟡 Check the vehicle display for drive or charge restrictions and schedule service promptly.

Kia EV9

P1B77

Warning

High Voltage Battery Precharging Fault on Kia EV6

Severity

Warning

What does P1B77 mean?

P1B77 on a Kia EV6 means High Voltage Battery Precharging Fault on the Hyundai/Kia E-GMP platform. Treat it as a warning-level battery DTC: driving or charging may be limited if READY mode, charging, or companion BMS/high-voltage warnings appear, so record the event and arrange qualified EV diagnosis.

Possible Causes

Battery management system (BMS) malfunction or precharge control fault
High-voltage battery cell imbalance that affects the precharge check
Battery temperature sensor fault or thermal data outside the expected range
High-voltage contactor or precharge circuit fault confirmed by EV diagnostic testing

Recommended Actions

1 Record the exact DTC P1B77, dashboard message, state of charge, temperature, and whether it happened during startup or charging
2 Reduce driving speed and avoid long trips if the EV warning returns, READY mode is unstable, or charging is limited
3 Scan for companion BMS, contactor, ICCU, 12V, or high-voltage isolation codes before clearing anything
4 Schedule service with a qualified EV technician and provide freeze-frame data plus the conditions that triggered the warning

This code applies to all vehicles. View generic P1B77 information →