P2E48: Hybrid/EV Electronics Coolant Pump B Overspeed

What it means

Hybrid/EV electronics coolant pump B reports a overspeed condition. Power electronics cooling on this branch is impaired.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Pump B circulates coolant through a dedicated hybrid or EV power-electronics branch. P2E48 sets when the module sees pump B running faster than expected, which may reflect an abnormal pump or driver response or a coolant-flow problem affecting the pump's operation.

Common causes

Most likely first.

1. Pump motor or driver fault
2. Air or coolant level issue

Symptoms

• Check-engine or hybrid-system warning light
• Reduced power or limited hybrid operation
• Possible power-electronics overheating warning

How to diagnose it

1. Save freeze-frame data and compare pump B's commanded and reported speeds with branch temperatures and other cooling-system live data.
2. Check the coolant level and inspect pump B's branch for leaks or air that could disrupt circulation.
3. Inspect pump B, the connector, and nearby wiring for damage, poor connections, or signs of coolant intrusion.
4. Check pump B's control and speed-feedback circuits against the manufacturer's specification.
5. If coolant and wiring checks pass, test the pump and driver using the vehicle manufacturer's procedure.

Common fixes

• Repair leaks and restore coolant level as specified for the vehicle.
• Bleed air from pump B's branch if present.
• Repair damaged wiring or connector faults affecting pump B control or speed feedback.
• Replace pump B or its driver if testing confirms the cause of the overspeed.

Can I keep driving?

Avoid heavy loads until pump B's speed and cooling performance are checked, because an abnormal pump response may reduce cooling and lead to power-electronics overheating or limited hybrid operation. Stop if an overheating warning appears.