What it means
The ECM detects a intermittent/erratic fault on the hybrid/ev battery pack coolant control valve position sensor 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
The battery coolant control valve changes coolant flow through the hybrid or EV battery pack loop, and its position sensor reports the valve's movement to the ECM. P0CE8 sets when that sensor signal becomes intermittent or erratic, so the module cannot consistently verify the valve position.
Common causes
Most likely first.
- Loose or damaged position sensor connector
- Damaged wiring causing an intermittent connection
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
- Check freeze-frame data and graph the battery coolant valve position on a scan tool to see whether the reading drops out or jumps during operation.
- With the vehicle powered down under the manufacturer's high-voltage safety procedure, inspect the sensor connector for looseness, corrosion, moisture, or damaged locking tabs.
- Inspect the valve sensor harness for cuts, chafing, stretched sections, or routing that could make the signal come and go.
- Monitor the signal while gently checking accessible harness sections for a change in reading, following the manufacturer's safety guidance.
- If the wiring remains stable, test the position sensor and valve through their operating range using the manufacturer's procedure.
Common fixes
- Reseat and secure a loose valve sensor connector.
- Repair damaged or chafed wiring that causes an intermittent signal.
- Replace a position sensor that drops out as the valve moves.
- Replace the coolant control valve if its sensor or mechanism is not separately serviceable.
Can I keep driving?
Limit driving and avoid high loads if power is reduced or a battery cooling warning appears, since an intermittent reading can disrupt coolant valve control. If the warning or reduced power recurs, stop in a safe place and arrange diagnosis.
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.