What it means
Hybrid/EV electronics coolant pump C exceeds the calibrated maximum speed. Mechanical load lost or rotor position offset.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Electronics coolant pump C circulates coolant through a hybrid or EV power-electronics cooling loop. The control module monitors its speed; this code sets when pump C exceeds its calibrated maximum, which can happen if it spins without the expected mechanical load or its rotor position is misread.
Common causes
Most likely first.
- Mechanical coupling broken
- Air pocket in coolant loop
Symptoms
- Check-engine or hybrid-system warning light
- Reduced power or limited hybrid operation
- Possible power-electronics overheating warning
How to diagnose it
- Use a scan tool to record freeze-frame data and compare pump C's reported speed with its commanded speed and related cooling-system temperatures.
- With the vehicle safely powered down and cool, check the relevant coolant level and look for signs of air in pump C's loop.
- Inspect accessible pump C connectors and wiring for looseness or damage that could distort speed or position feedback.
- Use the manufacturer's procedure to check whether pump C speed follows commands and whether the reported speed is plausible.
- If wiring and coolant-loop checks pass, test pump C for a broken mechanical coupling or rotor-position fault as specified by the manufacturer.
Common fixes
- Bleed trapped air from pump C's coolant loop using the manufacturer's procedure.
- Repair loose or damaged pump C wiring or connector connections.
- Repair or replace pump C if its mechanical coupling is broken.
- Replace or service pump C if its speed or rotor-position feedback fails the manufacturer's checks.
Can I keep driving?
Avoid continued driving if power is restricted or a power-electronics overheating warning appears, since pump C may not be cooling the electronics correctly. Stop safely if an overheating warning occurs.
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.