P01E3
Engine Coolant Temperature Sensor 3 Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 1
- AreaFuel and air metering
- E3
- FaultThe specific fault in that area
What it means
P01E3 is the generic code for a fault in the circuit of engine coolant temperature sensor 3. The engine control unit has seen a signal from this sensor that is outside the expected range, or that does not make sense against other temperature data. Which part of the cooling system sensor 3 monitors depends on the vehicle, so check the model-specific information.
Symptoms
- Engine warning light on
- Cooling fan running constantly or at odd times
- Temperature gauge reading wrongly, or not moving
- Poor fuel economy or rough running if the control unit uses this sensor for engine management
- Heater or thermal management working poorly on some models
- Hard starting when hot or cold on some models
Possible causes
- Damaged, chafed or corroded wiring to coolant temperature sensor 3 (open circuit, short to ground or short to voltage)likely
- Poor connection at the sensor plug or control unit connector (corrosion, loose or spread terminals, water ingress)likely
- Faulty coolant temperature sensor 3 with an incorrect or drifting resistancelikely
- Low coolant level or air in the cooling system, giving a false or erratic reading at the sensorpossible
- Fault in the thermal management system, such as a stuck thermostat or a faulty valve, causing readings that disagree with other sensorspossible
- Fault in the engine control unit sensor supply, ground or input circuitrare
- Outdated control unit software where the manufacturer has issued a fix for this faultrare
How to diagnose
- Read all stored and pending codes and the freeze frame data. Note engine temperature, load and whether other coolant temperature or thermal management codes are present.
- Check the coolant level when the engine is cold, and look for leaks or signs of air in the system.
- Find sensor 3 using model-specific information, as its location varies by engine. Inspect its wiring and connector for damage, corrosion, moisture and loose terminals.
- With the engine cold, compare the live data from sensor 3 with the other coolant and intake temperature readings. They should be close to each other.
- Check the live reading while warming the engine. Look for a reading that is stuck, jumps, or does not follow the other sensors.
- Unplug the sensor and check the supply voltage and ground at the harness against the manufacturer's specification.
- Measure the sensor's resistance and compare it with the manufacturer's temperature chart. Gently wiggle the wiring while monitoring for dropouts.
- Test the wiring between the sensor and control unit for continuity and shorts. Check for a software update only if the manufacturer lists one for this fault.
How to fix
- Repair or replace damaged wiring and fix any short or open circuit found.
- Clean or repair the connector and terminals, or replace the connector if it is corroded or worn.
- Replace coolant temperature sensor 3 if its readings are out of specification.
- Top up and bleed the cooling system to the correct level and repair any leak.
- Repair any faulty thermostat or thermal management component found during testing.
- Update the control unit software if an outdated version is a confirmed cause, or repair the control unit circuit if it is proven faulty.
Can I keep driving?
Medium severity
You can usually drive a short distance, but get it checked soon. Watch the temperature gauge, and stop at once if the engine overheats, if the warning light flashes, or if the coolant level is low.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.