Open circuit, chafed wire or damaged wiring between the control unit and the electronics coolant pump; Corroded, loose or pushed-out pins at the pump connector or control unit connector; Failed electronics coolant pump with an open internal motor or driver circuit; Blown fuse or faulty relay in the pump supply or control circuit; Low or contaminated coolant or air in the circuit causing the pump to be shut off or to fail; Fault inside the hybrid or EV control unit driver; Outdated control unit software where the manufacturer lists it as a known cause.

P0CE9

Hybrid/EV Electronics Coolant Pump A Control Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
C: AreaHybrid propulsion
E9: FaultThe specific fault in that area

What it means

P0CE9 means the hybrid or EV control unit has detected an open circuit in the control circuit for electronics coolant pump A. This pump circulates coolant through the power electronics, such as the inverter and DC-DC converter. The control unit saw no expected electrical response from the pump control circuit when it commanded the pump, so it set the code.

Symptoms

Hybrid or EV system warning light on the dashboard
Malfunction indicator lamp lit
Reduced power or limp mode
Power electronics temperature warning
Hybrid system or charging output limited
Coolant pump not audible when the system is ready

Possible causes

Open circuit, chafed wire or damaged wiring between the control unit and the electronics coolant pumplikely
Corroded, loose or pushed-out pins at the pump connector or control unit connectorlikely
Failed electronics coolant pump with an open internal motor or driver circuitlikely
Blown fuse or faulty relay in the pump supply or control circuitpossible
Low or contaminated coolant or air in the circuit causing the pump to be shut off or to failpossible
Fault inside the hybrid or EV control unit driverrare
Outdated control unit software where the manufacturer lists it as a known causerare

How to diagnose

Read all stored and pending codes and the freeze frame data, and note any other coolant, inverter or temperature codes.
Check the electronics coolant level and condition in the correct reservoir, following the manufacturer's procedure for the model, as the layout varies.
Inspect the pump wiring and connectors for chafing, corrosion, heat damage, water ingress and pushed-out pins.
Check the fuse and relay for the pump circuit against the wiring diagram for the specific model.
With the system active, command the pump using a suitable scan tool and listen and feel for pump operation.
Check for supply voltage, earth and control signal at the pump connector with a multimeter, following the wiring diagram.
Test the control wire for continuity and for shorts to earth or supply with the control unit and pump disconnected.
Check for any applicable software updates or technical bulletins for the model once the wiring and pump are proven good.

How to fix

Repair or replace damaged wiring and renew faulty connectors or terminals.
Clean and secure connector pins, and treat any water ingress source.
Replace the electronics coolant pump if it fails electrical or operational tests.
Replace the faulty fuse or relay after finding why it failed.
Top up or refill and bleed the electronics cooling circuit to the manufacturer's procedure.
Update or replace the control unit only if testing proves it faulty or an outdated software is a documented cause.

Can I keep driving?

Medium severity

The car may be driven carefully for a short distance, but power electronics can overheat without coolant flow, so the car may go into limp mode or shut down. Get it checked soon and stop if a temperature or hybrid system warning appears.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.