P0E50: Motor Electronics Coolant Pump B Control Circuit Intermittent/Erratic

P0E50 is the intermittent or erratic fault of the control circuit for coolant pump B, the second electric pump some hybrids use in the inverter and motor electronics cooling. No manufacturer documents P0E50 publicly. The closest published example is Ford's pump A version, P0E4F, stored when the pump's feedback leaves its expected frequency or duty cycle for over 1 s. Second pumps of this kind are in service: on the 2024 Jeep Compass 4xe, Stellantis bulletin 08-200-24 cures the pump B performance code P0C74 by reprogramming the hybrid control processors. CARB requires inverter cooling outputs to be monitored for circuit faults. Steady open, low and high faults of pump B are P0B38 to P0B3A. Short dropouts briefly reduce coolant flow and may trigger a power limit.

Symptoms

• Warning light that appears now and then
• Temporary power reduction under high load or heat

Most likely causes

• Intermittent contact at the pump B connector or a harness splice
• Pump B electronics producing an unstable signal
• Control module software evaluating the pump signal too strictly

What to check, in order

Start with the simplest. You can tick off each step.

1. With the engine cold, check the coolant level; never do this when the system is hot
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Check the actual temperature in live data
4. Make sure the fan comes on when it should
5. Check the thermostat and connector
6. Measure the sensor and replace it if its readings do not make sense

Good to know

• Repair difficulty: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P0E50 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• E: Subsystem depends on the code range
• 50: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0E50?

Watch the temperature gauge. If it climbs or a warning appears, stop the car in a safe place and turn off the engine: overheating can cause serious damage.

What causes code P0E50?

The most common causes are: intermittent contact at the pump B connector or a harness splice; pump B electronics producing an unstable signal; control module software evaluating the pump signal too strictly.

Related codes

• P0B38Motor Electronics Coolant Pump B Control Circuit/Open
• P0B39Motor Electronics Coolant Pump B Control Circuit Low
• P0B3AMotor Electronics Coolant Pump B Control Circuit High
• P0C74Motor Electronics Coolant Pump B Control Performance
• P0E4FMotor Electronics Coolant Pump A Control Circuit Intermittent/Erratic

Sources

• fordservicecontent.com: OBDSM1901 HEV
• static.nhtsa.gov: MC 11007842 0001
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.