What it means
The ECM detects a circuit low fault on the hybrid/ev battery pack coolant temperature sensor c circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Sensor C sends the battery-pack coolant temperature signal through its own circuit to the hybrid or EV control module. This low-circuit code means the module sees the signal held below its expected electrical range, which can happen with a signal short to ground or a sensor 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 power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Record freeze-frame data and check whether sensor C reads abnormally low compared with the other pack temperature readings.
- Inspect sensor C's harness and connector for pin damage, corrosion, moisture, or a wire rubbed through to ground.
- With the high-voltage system made safe using the vehicle's procedure, check the sensor signal wire for a short to ground.
- Test sensor C and its connector terminals for an internal short or poor contact, following the manufacturer's procedure.
- If the sensor and harness pass, verify the module-side circuit and grounds against the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose sensor C connector terminals where repair is permitted.
- Repair the signal wire if it is shorted to ground or damaged.
- Replace sensor C if it tests internally shorted.
- Repair the circuit connection at the control module if testing identifies a module-side fault.
Can I keep driving?
If the hybrid/EV warning is accompanied by reduced power or charging problems, avoid long trips and heavy acceleration and arrange prompt diagnosis. The vehicle may limit battery operation when it cannot trust sensor C's temperature signal.
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.