What it means
The HV battery temperature sensor M reports a range/performance 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 for battery management. This code sets when sensor M's reading is implausible or does not respond as expected, even though the circuit may remain electrically connected.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
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 note battery load, charging state, and ambient conditions when sensor M was judged out of range.
- Use a scan tool to compare sensor M's live temperature and response over time with other battery temperature channels.
- Inspect sensor M's accessible mounting and harness for displacement, poor contact with the monitored area, damage, or connector problems.
- Check for battery cooling or heating problems that could create a real temperature difference at the sensor M location.
- Test sensor M's response and circuit using the service procedure, comparing results with the manufacturer's specification.
Common fixes
- Restore sensor M to its specified mounting position if it has shifted.
- Repair a loose or damaged sensor M connection or harness.
- Correct a confirmed battery thermal-management problem affecting the monitored area.
- Replace sensor M if its reading remains outside the expected response after mounting and wiring are verified.
Can I keep driving?
Limit charging and high-load driving if the hybrid warning or reduced-power mode appears, because sensor M may be reporting battery temperature inaccurately. Stop safely if the vehicle limits propulsion or charging, and follow its battery-system warnings.
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.