Loose, corroded or damaged connector at coolant temperature sensor 3; Chafed, stretched or intermittently open or short-circuited wiring to the sensor; Failing coolant temperature sensor 3 giving an erratic output; Air pockets or low coolant level around the sensor causing unstable readings; Poor sensor reference voltage or ground supply shared with other sensors; Fault inside the engine control unit or the module that reads the sensor.

P01E7

Engine Coolant Temperature Sensor 3 Circuit Intermittent/Erratic.

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
E7: FaultThe specific fault in that area

What it means

P01E7 is a generic powertrain code meaning the control unit has detected an intermittent or erratic signal from engine coolant temperature sensor 3 or its circuit. The module saw the reading jump, drop out or change implausibly fast compared with the other temperature sensors and expected warm-up behaviour. Which part of the cooling system sensor 3 monitors depends on the make, model and engine.

Symptoms

Engine warning light on
Temperature gauge flickering, jumping or reading wrongly
Cooling fans running when the engine is cold or not running when hot
Hard starting or rough running when cold or hot
Poor fuel economy
Heater output varying or inconsistent

Possible causes

Loose, corroded or damaged connector at coolant temperature sensor 3likely
Chafed, stretched or intermittently open or short-circuited wiring to the sensorlikely
Failing coolant temperature sensor 3 giving an erratic outputlikely
Air pockets or low coolant level around the sensor causing unstable readingspossible
Poor sensor reference voltage or ground supply shared with other sensorspossible
Fault inside the engine control unit or the module that reads the sensorrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine temperature and load when the fault set, and look for other coolant temperature codes.
Check the coolant level when the engine is cold and look for leaks or signs of air in the system.
Find the location of sensor 3 for this specific engine from workshop data, then inspect its connector and wiring for damage, corrosion, moisture and rubbing.
With live data, watch sensor 3 from cold through warm-up and compare it with the other coolant temperature readings; look for sudden spikes or dropouts.
Wiggle the harness and connector while watching live data to see if the reading glitches.
Check the sensor's resistance or signal voltage against the manufacturer's temperature specification.
Test the sensor's reference voltage, signal wire and ground for continuity and shorts, as per the wiring diagram.
If all circuits and the sensor test fine, check for control unit software updates and fault history before considering the control unit.

How to fix

Clean, secure or replace the damaged connector or terminals at the sensor.
Repair or replace any damaged wiring between the sensor and the control unit.
Replace coolant temperature sensor 3 if its readings are erratic or out of specification.
Top up and correctly bleed the cooling system to remove air.
Repair the shared reference or ground fault found in the circuit.
Repair or replace the control unit only if it is confirmed faulty, or apply a manufacturer calibration update if one addresses this fault.

Can I keep driving?

Medium severity

The car can usually be driven short distances, but watch the temperature gauge closely as the engine may not manage cooling or fuelling correctly. Get it checked soon, and stop if the engine overheats.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.