What it means
The HV battery temperature sensor M reports a circuit intermittent/erratic 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
Sensor M monitors temperature at one area of the high-voltage battery, and the control module watches its signal for changes consistent with battery conditions. This code sets when the M reading becomes unstable or erratic, such as from a loose connector, intermittent contact under vibration, or a noisy ground reference.
Common causes
Most likely first.
- Connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
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
- Retrieve freeze-frame data and review Sensor M live temperature while comparing it with other battery temperature channels for sudden jumps or dropouts.
- With the vehicle powered down as specified by the manufacturer, inspect Sensor M's connector for incomplete seating, corrosion, or damaged pins.
- Inspect the Sensor M harness and its ground reference for looseness, chafing, or damage that could change with vibration.
- Using the manufacturer's safe diagnostic procedure, monitor the M signal while checking accessible wiring and connector movement for dropouts.
- If the connection and harness remain stable, test the sensor and ground circuit, then the module input, according to the manufacturer's procedure.
Common fixes
- Fully seat and secure the Sensor M connector.
- Clean or repair damaged or corroded connector terminals.
- Repair a loose or damaged ground reference or harness section affecting Sensor M.
- Replace Sensor M if its signal remains erratic with sound wiring and connections.
Can I keep driving?
Intermittent battery temperature data can cause unpredictable limits on power or charging. Keep driving gentle and brief, and stop if the vehicle displays a stop warning or loses power significantly.
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.