What it means
Voltage on the third coolant pump control line is below the expected window. Usually a short to ground or a shorted motor winding.
At a glance
- Usually lights the check-engine light
How it works
Coolant Pump C circulates coolant through a separate cooling loop, and the control module monitors the electrical condition of its control line. This code sets when that line reads below its expected range, which can happen if the wire is grounded or the pump winding is internally shorted.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in pump motor winding
- Connector pins corroded - high contact resistance
Symptoms
- Engine or powertrain warning light may come on
- Temperature warning may appear if the affected cooling loop overheats
- Cooling performance may be reduced in the affected system
How to diagnose it
- Record freeze-frame data and check live data for Pump C command and fault status to see when the low reading occurs.
- With the system cool, inspect Pump C's connector and control-line wiring for corrosion, damaged insulation, pinched sections, or contact with ground.
- Check the connector pins for corrosion or poor contact, since added resistance can disrupt the control signal.
- Test the control wire for a short to ground using the manufacturer's procedure and specification.
- If the wiring checks out, test the Pump C motor winding and control circuit against the manufacturer's specification.
Common fixes
- Clean or repair corroded Pump C connector pins and restore a secure connection.
- Repair or replace control-line wiring shorted to ground.
- Replace Pump C if its motor winding is internally shorted.
Can I keep driving?
Avoid driving if a temperature warning appears or the affected loop is not cooling; overheating can damage components. If there are no temperature symptoms, keep trips short and monitor the temperature warning closely.
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.