Open or damaged wire in the coolant pump control circuit; Failed coolant pump motor or internal control module; Corroded or loose electrical connector at the pump or control module; Blown fuse or failed relay supplying power to the pump circuit; Faulty hybrid/EV control module driver circuit; Coolant contamination or blockage causing pump overload and circuit stress

DTC codes / P0Cxx · Hybrid propulsion / P0CE9

P0CE9Hybrid/EV Electronics Coolant Pump A Control Circuit/Open

Q: What does code P0CE9 mean?

Hybrid/EV Electronics Coolant Pump A Control Circuit/Open. P0CE9 indicates that the hybrid or electric vehicle control module has detected an open circuit or control fault in the electrical path for coolant pump 'A', which circulates liquid coolant through the power electronics. The computer monitors the pump's control circuit and sets this code when the expected voltage or current feedback does not match commanded operation.

P0CE9 indicates that the hybrid or electric vehicle control module has detected an open circuit or control fault in the electrical path for coolant pump 'A', which circulates liquid coolant through the power electronics. The computer monitors the pump's control circuit and sets this code when the expected voltage or current feedback does not match commanded operation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the hybrid system warning light or service vehicle soon message
Reduced electric driving range or forced engine operation due to overheating protection
Coolant pump may not run, leading to elevated inverter or motor temperatures
Possible power reduction or limp mode if component temperatures rise
Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

Open or damaged wire in the coolant pump control circuit
Failed coolant pump motor or internal control module
Corroded or loose electrical connector at the pump or control module
Blown fuse or failed relay supplying power to the pump circuit
Faulty hybrid/EV control module driver circuit
Coolant contamination or blockage causing pump overload and circuit stress

How to diagnose and fix it

Scan all modules for related codes and record freeze-frame data to understand when the fault occurs
Inspect the coolant pump connector and wiring for corrosion, chafing, or loose pins
Check the pump circuit fuse and relay, and verify power and ground at the pump connector
Command the pump on with a scan tool and measure control circuit voltage and current draw
Perform a resistance test on the pump motor and compare to manufacturer specifications
If the circuit tests good, substitute a known-good pump or module to isolate the failed component
Clear codes and verify repair by running the pump through a complete drive cycle

What the coolant pump circuit test reveals

A pump that spins freely by hand can still have an open internal control circuit, so electrical testing is more reliable than mechanical feel.
The control module often sets this code based on current feedback rather than a simple voltage check, so a partially shorted pump may not trigger it until temperatures rise.
Corrosion inside the pump connector is a frequent cause that looks like a failed pump, and cleaning the terminals can resolve the fault without replacement.
Some vehicles use the same pump for both electronics and cabin heating, so a fault may only appear when the climate system requests coolant flow.
After repairs, the pump may need to be commanded on with a scan tool to bleed air from the cooling system, or the code can reset immediately.

Can I keep driving with P0CE9?

It is not advisable to continue driving with this code because a failed coolant pump can lead to overheating of hybrid components and costly damage. If the warning light is on, limit driving to short distances and avoid high-load or high-temperature conditions until the fault is repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.