P01E5

What it means

P01E5 is a generic code meaning the control unit has detected a low voltage or signal in the circuit for Engine Coolant Temperature Sensor 3. The signal sits below the expected range, which usually points to a short to earth or a sensor that is reading falsely hot. Which part of the cooling system sensor 3 monitors depends on the vehicle and engine.

Symptoms

• Engine warning light on
• Temperature gauge reading high, erratic or not moving
• Cooling fans running constantly or at the wrong time
• Poor fuel economy or rough running
• Hard starting or an odd idle when cold
• Reduced performance if the control unit enters a protective strategy

Possible causes

• Sensor 3 internally faulty and reading as extremely hotlikely
• Signal wire chafed and shorted to earthlikely
• Damaged, corroded or water-contaminated sensor connectorpossible
• Signal wire shorted to another earth or sensor return wirepossible
• Reference voltage or earth fault on the shared sensor supplypossible
• Fault inside the control unit or its software calibrationrare

How to diagnose

1. Read all stored and pending codes and look at the freeze frame data, noting engine temperature and conditions when the code set.
2. Find out from the manufacturer's data where sensor 3 is fitted on this model and engine, as its location and role vary.
3. Compare the live reading from sensor 3 with the other coolant temperature sensors on a cold engine, which should all be close to ambient.
4. Inspect the sensor, connector and wiring for chafing, melted insulation, corrosion, moisture or pin damage.
5. Unplug the sensor with the ignition on and see whether the reading changes to a very low or open-circuit value, which would show whether the fault is in the sensor or the wiring.
6. Measure the sensor resistance and compare it with the specification at the current temperature.
7. Check the wiring for a short to earth and check the reference voltage and earth at the connector against the wiring diagram.
8. If wiring and sensor test fine, check for any software update that applies to the vehicle before suspecting the control unit.

How to fix

• Replace sensor 3 if its resistance is out of specification or it reads falsely hot.
• Repair or replace the damaged wiring section where it is shorted to earth.
• Clean or replace a corroded or damaged connector and make sure it is sealed and locked.
• Restore the reference voltage or earth supply if the fault is in the shared sensor circuit.
• Carry out any applicable control unit software update if the manufacturer lists it as a fix for this fault.
• Clear the code after repair and road test to confirm it does not return.

Can I keep driving?

Nearby codes

• P01E4GenericEngine Coolant Temperature Sensor 3 Circuit Range/Performance
• P01E6GenericEngine Coolant Temperature Sensor 3 Circuit High