Cooling

P01EE — Engine Coolant Heater B Control Circuit High

Severity: low Safe to drive

What P01EE means

The engine control module switches the electric coolant heater B on and off through a relay or driver and monitors the control circuit. P01EE sets when the voltage in that circuit is higher than expected. Typical causes are a short to voltage, a wiring fault, or a failed heater, relay or driver.

Symptoms

  • Check Engine light on
  • Slow engine warm-up in cold weather
  • Weak cabin heat in winter
  • Higher fuel use during warm-up
  • Heater not turning on, or staying on constantly

Possible causes

  1. Wiring shorted to voltage or damaged in the heater B control circuit
  2. Failed coolant heater B assembly
  3. Corroded, loose or damaged connector
  4. Faulty relay or driver controlling the heater
  5. Rarely, a faulty ECM

How to diagnose

  1. Read all codes and freeze frame data, and look for related power or coolant temperature codes
  2. Inspect the harness and connectors at the heater and relay for chafing, heat damage, corrosion and moisture
  3. Check the fuse and relay for the heater circuit
  4. Unplug the heater and measure control circuit voltage per the factory wiring diagram
  5. Test the wiring for a short to voltage and for continuity back to the ECM
  6. Measure heater resistance and compare it to specification
  7. Run an active heater test with a scan tool if available
  8. If wiring and heater test good, evaluate the ECM

Common fixes

  • Repair or replace damaged wiring and connectors
  • Replace a faulty relay or fuse
  • Replace the coolant heater B assembly
  • Clean and secure the electrical connections
  • Replace or reprogram the ECM only if confirmed faulty

Questions and answers

What does P01EE mean?

It means high voltage in the control circuit of coolant heater B. Wiring, a connector, the relay or the heater itself is usually at fault.

Can I drive with P01EE?

Usually yes, as the engine isn't at immediate risk. Cold-weather warm-up and cabin heat may be poor, so get it checked soon.

How do I clear P01EE?

Clearing it with a scan tool only helps temporarily. Fix the cause first or the code will return.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.