P2B6B: Coolant Pump D Control Module Overtemperature

What it means

Coolant pump D reports a control module overtemperature 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’s control module operates the pump and may protect itself by limiting operation when it gets too hot. P2B6B sets when the module detects an overtemperature condition, which can result from high under-bonnet heat or a blocked path that prevents the module from shedding heat.

Common causes

Most likely first.

1. Ambient or under-bonnet temperature too high
2. Module cooling path blocked

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

1. Record freeze-frame data and review pump D module temperature, pump command, and coolant temperatures to see when the overtemperature occurs.
2. With the system cool, inspect the control module’s cooling path for blocked airflow, debris, or anything obstructing heat transfer.
3. Inspect the module and pump D connectors and nearby harness for heat damage, corrosion, or loose connections.
4. Check whether the fault returns after the area has cooled, and compare module temperature readings with other available temperature data for plausibility.
5. Test the module’s power, ground, and cooling arrangement according to the manufacturer’s procedure before concluding the module has failed.

Common fixes

• Clear debris or an obstruction from the pump D module’s cooling path.
• Secure or repair a loose or heat-damaged module connector.
• Repair wiring or power and ground faults that cause abnormal module heating.
• Replace the pump D control module if it continues to report overtemperature with its cooling path clear and circuits verified.

Can I keep driving?

Avoid demanding driving and monitor engine temperature; stop if it rises or a coolant warning appears. If pump D is limited by its hot control module, circulation may fall and the affected loop can overheat.