What it means
Coolant pump D reports a control circuit/open condition. Coolant circulation through the affected loop cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Coolant pump D circulates coolant through its assigned loop, and its control circuit carries the command needed to operate the pump. P2B66 sets when the module detects an open control path, so pump D may not receive the command and coolant circulation in that loop can be lost.
Common causes
Most likely first.
- Open in control wire
- Open pump motor
- Pin pushed back out of connector body
Symptoms
- Check-engine light
- Engine or a coolant-cooled component may run hotter than usual
- Cabin heat or cooling performance may be reduced
How to diagnose it
- Check freeze-frame data and live pump D command and status, along with temperatures for its coolant loop, to see whether the pump failed to respond.
- With the vehicle safely powered down, inspect pump D's control connector for a pin pushed back into the housing, loose fit, or corrosion.
- Inspect the control wire and harness between pump D and the module for breaks, chafing, or disconnected sections.
- Use the wiring diagram to check control-circuit continuity and connector pin contact while gently moving the harness.
- If the control wiring is intact, test the pump motor and module output using the manufacturer's procedure to locate the open.
Common fixes
- Reseat a pushed-back pump D connector pin and secure the connector.
- Clean corroded terminals and restore proper pin contact.
- Repair an open or damaged pump D control wire.
- Replace pump D if its motor winding is open and the circuit to it is intact.
Can I keep driving?
Limit driving and monitor temperature because pump D may not circulate coolant through its loop; stop safely if the engine or affected component overheats. The vehicle may limit power, and continued overheating can cause damage.
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.