P2D0C: Motor Electronics Coolant Pump C Underspeed

What it means

Motor electronics coolant pump C reports a underspeed condition. Power electronics cooling is impaired.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Motor electronics coolant pump C circulates coolant through power electronics such as the inverter. The control module compares the pump’s reported speed with its requested speed and sets this code when pump C runs slower than expected.

Common causes

Most likely first.

1. Mechanical load increased
2. Supply voltage low under load

Symptoms

• Check-engine or hybrid-system warning
• Power limited warning
• Reduced performance under load

How to diagnose it

1. Read freeze-frame data and pump C requested and reported speed to see when the underspeed occurred.
2. With the system safely powered down as specified by the manufacturer, inspect pump C and its coolant hoses for blockage, leaks, kinks, or signs of binding.
3. Check the coolant level and look for air or restrictions in the power-electronics cooling circuit.
4. Inspect pump C’s power and ground wiring and connectors for looseness, corrosion, or damage.
5. Measure pump C supply voltage while it is commanded on and compare it with the manufacturer’s specification.
6. If supply and coolant flow are satisfactory, test pump C for mechanical drag or an internal speed-sensing fault.

Common fixes

• Restore the correct coolant level and bleed the circuit using the manufacturer’s procedure.
• Clear a restriction or repair a kinked or damaged coolant hose.
• Repair loose, corroded, or damaged pump C wiring or connections.
• Replace pump C if it binds or cannot reach commanded speed despite correct supply and flow.

Can I keep driving?

Avoid heavy loads and stop driving if a power-limited or hybrid-system warning appears, since inadequate power-electronics cooling can lead to further power reduction or overheating. Arrange prompt diagnosis.