OBD-II fault code

P2E46: Hybrid/EV Electronics Coolant Pump B Overspeed - Dry Run

What it means

Hybrid/EV electronics coolant pump B reports a overspeed - dry run 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 hybrid or EV power-electronics cooling branch. P2E46 indicates the module sees pump B speed exceeding the expected range in a dry-run condition, which can occur when the pump is not moving coolant properly, such as when the branch is low on coolant or contains air.

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. Capture freeze-frame data and compare pump B's commanded and reported speed with coolant-temperature and pump-status live data.
  2. Check the coolant level and look for leaks in pump B's branch; a low level can leave the pump running without a full coolant supply.
  3. Check for air in the branch and follow the vehicle's specified filling and bleeding procedure if needed.
  4. Inspect pump B, its connector, and nearby wiring for damage, loose connections, or evidence of leakage.
  5. If coolant supply and wiring are sound, test pump B and its driver against the manufacturer's diagnostic procedure.

Common fixes

  • Repair a leak and restore the coolant level using the specified coolant and procedure.
  • Bleed air from pump B's cooling branch using the vehicle's specified procedure.
  • Repair damaged wiring or connector faults affecting pump B speed control or feedback.
  • Replace pump B or its driver if testing confirms it is causing the dry-run speed condition.

Can I keep driving?

Avoid driving under load until the coolant level and pump B operation are checked; dry running can leave power electronics without effective cooling and cause overheating or reduced power. Stop safely if an overheating warning appears.

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.

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