What it means
Voltage on the engine coolant pump control line is above the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The engine coolant pump control circuit carries the module's command to operate the pump. The module monitors the circuit voltage and sets P26CD when it is higher than its expected range, which can happen if the control wire is shorted to power or the pump winding or connector is faulty.
Common causes
Most likely first.
- Control wire shorted to B+
- Open motor winding
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may be on
- Engine temperature may rise or overheat
- Cooling-system warning may appear
How to diagnose it
- Record freeze-frame data and check live pump command and circuit voltage to see when the high reading occurs.
- Inspect the coolant pump connector and control harness for chafing, moisture, corrosion, loose pins, or a pushed-back terminal.
- With the circuit monitored, gently move the harness near the pump and connector to see whether the voltage changes or the fault returns.
- Check the control wire for an unintended connection to battery power, following the vehicle wiring diagram.
- Test the pump winding and connector continuity against the manufacturer's specification to distinguish an open winding from a wiring fault.
Common fixes
- Repair chafed or damaged control-wire insulation.
- Clean or repair corroded, loose, or pushed-back connector terminals and restore the seal.
- Repair a control wire shorted to battery power.
- Replace the coolant pump if its winding is open.
Can I keep driving?
Because the pump may not operate correctly, avoid driving if temperature rises or a cooling warning appears; stop safely and shut the engine off if it overheats. Continued overheating can damage the engine.
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.