P2B64: Coolant Pump B Control Module Overtemperature

What it means

Coolant pump B 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 B's control module operates or regulates the pump, while monitoring its own temperature to protect the electronics. P2B64 sets when that module overheats, which can interrupt pump B control and reduce coolant flow through its assigned loop.

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. Check freeze-frame data and live pump B status and coolant temperatures to see whether the module overheated during high ambient or under-bonnet temperatures.
2. With the vehicle cool and safely powered down, inspect the pump control module's cooling path for blocked airflow, debris, or other visible obstruction.
3. Inspect pump B and module connectors for loose contacts or damage that could increase electrical load or impair cooling.
4. Check pump current and supply wiring under the manufacturer's procedure to identify an electrical overload contributing to module heat.
5. If airflow and wiring are sound but the module repeatedly overheats, test pump B and its control module against the manufacturer's specification.

Common fixes

• Clear debris or obstruction from the pump control module's cooling path.
• Repair poor connector contacts or wiring faults that contribute to excess module heating.
• Replace a pump B control module that fails its temperature or operation tests.
• Replace pump B if it is drawing excessive current and causing the module to overheat.

Can I keep driving?

Do not continue driving if the affected loop or engine temperature rises; stop safely and allow the vehicle to cool. Repeated module overheating can interrupt pump operation and lead to coolant-related damage.