P2E47: Hybrid/EV Electronics Coolant Pump B Underspeed

What it means

Hybrid/EV electronics coolant pump B reports a underspeed 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 branch that cools hybrid or EV power electronics. This code sets when the module detects pump B turning more slowly than expected, so coolant flow in that branch may be insufficient.

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. Record freeze-frame data and check live data for pump B commanded speed, reported speed, and power-electronics temperatures.
2. Check coolant level and inspect pump B's branch for leaks or air that could restrict effective circulation.
3. Inspect the branch and pump B for visible obstructions, damage, or loose connections.
4. Check pump B wiring and connector condition, then test its power, control, and feedback circuits against the manufacturer's specification.
5. If coolant flow and circuit checks do not explain the low speed, test pump B and its driver using the manufacturer's procedure.

Common fixes

• Repair leaks and restore the coolant level with the specified procedure.
• Bleed air from pump B's branch or clear a confirmed flow restriction.
• Repair damaged or loose pump B wiring and connector connections.
• Replace a pump B motor or driver confirmed to be causing underspeed.

Can I keep driving?

Keep driving to a minimum and avoid high-load operation, since slow circulation can overheat power electronics and lead to reduced hybrid output. Stop if an overheating warning or power limitation occurs.