What it means
The battery monitor module measures battery temperature above the safe upper threshold - charging is derated or stopped to prevent thermal runaway. Causes are heat soak from a hot engine bay, hard charging on a depleted battery, or a faulty sensor.
At a glance
- Usually lights the check-engine light
How it works
The battery monitor module tracks battery temperature to help protect the battery during charging. This code sets when the reported battery temperature exceeds the system's upper limit, so charging may be reduced or stopped to limit heat-related damage.
Common causes
Most likely first.
- High battery temperature from hot ambient conditions or engine heat
- Battery overheating during charging
- Battery temperature sensor fault
- Battery-monitor module fault
Symptoms
- Battery or charging warning light may appear
- Charging may be limited
- Start-stop system may be unavailable
How to diagnose it
- Record freeze-frame data and read battery temperature and charging data with a scan tool to confirm when the high-temperature condition was reported.
- Check whether the battery is actually hot and inspect for heat exposure from the engine bay, recent heavy charging, or signs of battery damage.
- Inspect the battery temperature sensor, its mounting, and its connector for damage or poor contact that could produce a falsely high reading.
- Check sensor wiring for shorts, chafing, corrosion, or loose terminals, then compare the reading with the manufacturer's specification.
- If the battery temperature and sensor circuit check out, follow the manufacturer's procedure to test the battery monitor module.
Common fixes
- Allow an overheated battery to cool and address the source of excessive heat.
- Secure or reconnect the battery temperature sensor and its connector.
- Repair damaged or shorted temperature-sensor wiring.
- Replace a temperature sensor or battery monitor module only if it fails the manufacturer's checks.
Can I keep driving?
Avoid strenuous driving or repeated attempts to charge a battery that is genuinely overheating; heat can damage the battery and create a safety hazard. If the battery is hot, swollen, leaking, or giving off an unusual smell, stop in a safe place and seek assistance.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.