What it means
The motor electronics coolant pump B control signal drops out or jumps intermittently. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Motor electronics coolant pump B circulates coolant to help control the temperature of the vehicle’s motor electronics. The control module monitors pump B’s control circuit and sets P0E50 when its signal drops out or behaves erratically, often as a connector or wiring contact changes with movement or vibration.
Common causes
Most likely first.
- Connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Hybrid/EV system warning light may turn on
- Reduced power or limited electric drive
- Cooling system warning may appear
How to diagnose it
- Review freeze-frame and live data for pump B command and circuit status, noting whether the fault appears during operation or after vibration or movement.
- With the vehicle safely powered down as specified by the manufacturer, inspect pump B’s connector for incomplete seating, moisture, corrosion, damaged seals, or pushed-back pins.
- Trace pump B’s harness for chafing, pinching, or damage, and gently move accessible wiring while monitoring circuit status for dropouts.
- Check the pump B circuit ground and connections for unstable contact using the manufacturer’s wiring information.
- If the wiring and connector remain sound, test pump B and its control circuit against the manufacturer’s diagnostic procedure.
Common fixes
- Reseat and secure pump B’s connector.
- Repair damaged or chafed wiring in pump B’s control circuit.
- Clean or repair corroded connector terminals and restore a sound ground connection.
- Replace a connector or terminal that cannot maintain contact.
- Replace pump B only if testing confirms the pump itself causes the intermittent signal.
Can I keep driving?
Avoid demanding acceleration or extended driving if reduced electric drive or a cooling warning appears; an intermittent pump B control signal can compromise motor-electronics cooling. Stop safely if a temperature warning or significant power loss occurs and arrange prompt diagnosis.
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.