Cooling

P01E4 — Engine Coolant Temperature Sensor 3 Circuit Range/Performance

Severity: medium Drive with care, to a shop

What P01E4 means

The engine control module compares the signal from coolant temperature sensor 3 with expected values and with other temperature sensors. If the signal is out of range, stuck or does not match how the engine warms up, it sets P01E4. The location of sensor 3 varies by manufacturer; it may be on the engine, a hose or a secondary coolant circuit.

Symptoms

  • Check Engine light on
  • Erratic or inaccurate coolant temperature readings
  • Cooling fans running too early, too late or constantly
  • Rough idle or reduced power
  • Hard starting or higher fuel use when warm
  • Possible overheating

Possible causes

  1. Faulty coolant temperature sensor 3
  2. Open circuit or short to ground or voltage in the sensor wiring
  3. Corroded or loose connector
  4. Low coolant or an air pocket near the sensor
  5. Thermostat fault causing real temperature to differ from expected
  6. Rarely, an ECM fault or poor ECM power or ground

How to diagnose

  1. Scan all codes and review freeze frame data for related temperature or cooling codes
  2. Check coolant level and condition on a cold engine
  3. Compare sensor 3 readings on a scan tool with other temperature sensors, cold and warm
  4. Inspect the connector and harness for corrosion, chafing and heat damage
  5. Check reference voltage and ground at the sensor connector using the wiring diagram
  6. Measure sensor resistance and compare it with the vehicle's specification
  7. Test thermostat operation and cooling fans
  8. If wiring and sensor are good, check ECM power and grounds

Common fixes

  • Replace coolant temperature sensor 3
  • Repair wiring or replace the connector
  • Top off or replace coolant and bleed air from the system
  • Replace a faulty thermostat
  • Fix ECM power or ground faults; reprogram or replace the ECM only if confirmed

Questions and answers

What does P01E4 mean?

The ECM sees the signal from coolant temperature sensor 3 as implausible or out of range. It is usually a sensor or wiring problem rather than actual overheating.

Can I drive with P01E4?

Briefly, if the temperature gauge stays normal. If you see overheating or odd fan behavior, stop to avoid engine damage.

How do I clear P01E4?

Fix the cause first, then clear the code with a scan tool. If the fault remains, 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.