Cooling system failure (low coolant, blocked radiator, or pump failure). Ambient temperature extremes affecting sensor calibration. Faulty temperature sensor providing inaccurate readings.

Avoid aggressive driving and schedule a diagnostic appointment within the next 1–3 days. Scan for all DTCs with an OBD-II scanner — note any related codes stored alongside P1B03. Check coolant level, coolant flow, and cooling fan operation.

Is it safe to drive with P1B03?

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

Hyundai IONIQ 5

P1B03

Warning

Auxiliary Battery Temperature Sensor Circuit Malfunction

Severity

Warning

What does P1B03 mean?

P-code P1B03 means "Auxiliary Battery Temperature Sensor Circuit Malfunction". It is a manufacturer-specific diagnostic trouble code (DTC) in the battery system. An abnormal temperature condition has been detected in the auxiliary battery temperature sensor circuit malfunction — the system may be overheating or running too cold. This warning should be addressed within the next few days to avoid further damage. This code applies to OBD-II compliant electric and hybrid vehicles.

Possible Causes

Cooling system failure (low coolant, blocked radiator, or pump failure)
Ambient temperature extremes affecting sensor calibration
Faulty temperature sensor providing inaccurate readings
Thermal management system component failure

Recommended Actions

1 Avoid aggressive driving and schedule a diagnostic appointment within the next 1–3 days
2 Scan for all DTCs with an OBD-II scanner — note any related codes stored alongside P1B03
3 Check coolant level, coolant flow, and cooling fan operation
4 Inspect the temperature sensor and its wiring for damage or corrosion
5 Clear the DTC, road-test the vehicle, and re-scan to confirm whether the fault returns
6 If the fault persists after inspection and clearing, consult an EV-certified technician for component replacement

This code applies to all vehicles. View generic P1B03 information →