P26D7: Engine Coolant Pump Clutch Performance/Stuck Off

What it means

The coolant pump clutch is commanded on but does not engage. Coolant flow is missing under load, leading to overheating.

At a glance

• Usually lights the check-engine light

How it works

The coolant pump clutch lets the module engage the pump when extra coolant flow is needed, such as under engine load. The module compares its command with the clutch or pump response; this code sets when the clutch is commanded on but fails to engage, so coolant flow may be inadequate.

Common causes

Most likely first.

1. Worn friction surfaces enlarge air gap
2. Weak solenoid magnetic force
3. Carbon or debris buildup preventing free movement

Symptoms

• Check-engine light may be on
• Engine may overheat, especially under load
• Cooling-system warning may appear

How to diagnose it

1. Check freeze-frame data and coolant temperature to see when the clutch was commanded on and whether overheating began under load.
2. Inspect the coolant pump clutch, its connector, and nearby wiring for damage, contamination, or loose connections.
3. Use a scan tool to command the clutch on and check whether the pump responds or coolant temperature rises abnormally.
4. Check the clutch supply and control circuit while commanded on, looking for a poor connection or wiring fault.
5. Test the clutch coil and mechanical movement against the manufacturer's specification for an open, weak coil, excessive air gap, or sticking parts.

Common fixes

• Clean and secure the clutch connector and repair damaged wiring.
• Remove debris or carbon buildup that is preventing the clutch from moving freely, if serviceable.
• Repair a weak or damaged clutch coil circuit.
• Replace the worn or defective coolant pump clutch assembly.

Can I keep driving?

Avoid heavy loads and stop safely if the engine temperature rises or a cooling-system warning appears; inadequate pump flow can quickly cause overheating and engine damage. Arrange diagnosis promptly.