What it means
The HV battery temperature sensor M reports a circuit fault. Cell-group temperature monitoring impaired on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Hybrid or EV battery temperature sensor M measures the temperature of a particular monitored cell-group area so the battery management system can control charging and power safely. This code sets when sensor M's electrical circuit is faulty, leaving that temperature channel unreliable.
Common causes
Most likely first.
- Failed temperature sensor
- Open, shorted, or damaged wiring
- Loose or corroded connector
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Record freeze-frame data and scan for other battery temperature, voltage, and isolation codes before clearing faults.
- Use a scan tool to compare sensor M's temperature reading with the other battery temperature channels and ambient conditions.
- Inspect the accessible sensor M connector and harness for looseness, corrosion, moisture, pin damage, or chafing, following high-voltage service precautions.
- Test the sensor M circuit for an open, short, or poor connection using the vehicle's service procedure.
- If the wiring and connector are sound, test sensor M against the manufacturer's specification before considering replacement.
Common fixes
- Reseat and secure the sensor M connector.
- Repair damaged wiring or corroded terminals in the sensor M circuit.
- Replace temperature sensor M if its circuit is intact and the sensor fails testing.
- Clear the code and verify sensor M reports plausibly alongside the other battery temperature channels.
Can I keep driving?
Avoid charging or high-load driving if the hybrid system warning or reduced-power mode is active, since the battery management system cannot rely on the temperature reading for that monitored area. Follow the vehicle's warnings and stop safely if it limits or interrupts propulsion.
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.