P3446critical severityPowertrain
BMS Thermal Runaway Detection System Fault
on 2010 Toyota Highlander 3.3L V6 Hybrid · AWD
What this code means
The BMS thermal runaway detection and mitigation system has a sensor or circuit fault. This safety system monitors for rapid cell temperature rise.
Symptoms
- Critical safety system warning
- Vehicle may restrict operation
- Battery monitoring in degraded mode
- Potential safety risk
- Service required immediately
Common causes
- Thermal runaway sensor failure
- Sensor wiring fault
- BMS safety monitor circuit error
- Gas detection sensor failure
- Pressure vent sensor malfunction
Diagnostic steps
- Check thermal runaway sensor status in BMS
- Test individual detection sensors
- Inspect sensor wiring connections
- Verify BMS safety monitor self-test results
- Check gas detection sensor calibration
Repair notes
SAFETY CRITICAL. Repair immediately. Replace thermal runaway detection sensors. This system protects against catastrophic battery failure.
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P0015
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