What it means
The control module detected a low signal condition in the drive motor A coolant temperature sensor circuit. The cause and vehicle response depend on the vehicle.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The drive motor A coolant temperature sensor reports coolant temperature to the hybrid or EV control module. The module compares its signal with the expected sensor range; this code sets when the signal is too low, which may be interpreted as an implausibly cold reading or an electrical fault.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Use a scan tool to record freeze-frame data and compare drive motor A coolant temperature with other available temperature readings; note whether the value is implausibly low.
- With the vehicle powered down according to its service procedure, inspect the drive motor A temperature sensor connector and harness for corrosion, damage, moisture, or a signal wire touching ground.
- Check whether the sensor reading changes plausibly as the motor warms, using live data and the vehicle's safe operating procedure.
- Test the sensor and its signal circuit for a short to ground, and check connector contact quality against the manufacturer's specification.
- If the wiring and connector pass, test the sensor and module-side circuit using the manufacturer's diagnostic procedure to locate the source of the low signal.
Common fixes
- Repair a signal wire shorted to ground.
- Clean or repair corroded sensor connector pins and restore secure contact.
- Replace a coolant temperature sensor that tests internally shorted.
- Repair damaged harness wiring or a faulty module-side circuit identified by testing.
Can I keep driving?
Avoid hard acceleration and continued driving if motor power is reduced or the hybrid system warns of overheating; the vehicle may enter limp mode or shut down. Stop safely if a temperature warning appears or propulsion becomes unreliable.
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.