Engine Coolant Heater B Control Circuit Low

Common symptoms

What you'll notice

• Check the wiring and connections related to the engine coolant heater circuit.
• Inspect the engine coolant heater control module for any faults or malfunctions.
• Replace the engine coolant heater if it is damaged or not functioning properly.
• Ensure that the engine coolant level is within the recommended range and top up if necessary.
• Have the engine control module (ECM) checked for any errors or issues related to the engine coolant heater circuit.

Common causes

Most likely first

1. Faulty engine coolant heater control module
2. Short circuit in the engine coolant heater control circuit
3. Open or high resistance in the engine coolant heater control circuit
4. Faulty engine coolant temperature sensor
5. Issues with the engine coolant heater itself

How to diagnose & fix

Work through it in order

1. Engine overheating
2. Poor heater performance
3. Check engine light illuminates
4. Hard starting in cold weather
5. Inconsistent or erratic engine performance