Intermittent connection at the sensor connector, such as corrosion, bent pins or a loose fit; Damaged, chafed or heat-affected wiring between the sensor and the control unit; Failing cylinder head temperature sensor with an internal intermittent fault; Poor sensor reference supply or ground shared with other sensors; Coolant level low or air in the cooling system causing unstable temperature readings at the sensor; Moisture or coolant ingress into the connector or loom; Fault within the engine control unit.

P017E

Cylinder Head Temperature Sensor A 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
7E: FaultThe specific fault in that area

What it means

P017E means the engine control unit has detected an intermittent or erratic signal from cylinder head temperature sensor A. The reading jumped, dropped out or behaved implausibly compared with expected values or other temperature inputs, rather than staying steadily out of range. Sensor location, number of sensors and how the value is used vary by model and engine.

Symptoms

Engine warning light on
Temperature gauge reading erratic or dropping to zero (if the gauge uses this signal)
Cooling fans running at unexpected times or constantly
Poor or uneven running, hesitation or reduced power if the engine enters a protection strategy
Fault appearing and disappearing, often with vibration or when the engine is hot
Slightly poorer fuel economy

Possible causes

Intermittent connection at the sensor connector, such as corrosion, bent pins or a loose fitlikely
Damaged, chafed or heat-affected wiring between the sensor and the control unitlikely
Failing cylinder head temperature sensor with an internal intermittent faultlikely
Poor sensor reference supply or ground shared with other sensorspossible
Coolant level low or air in the cooling system causing unstable temperature readings at the sensorpossible
Moisture or coolant ingress into the connector or loompossible
Fault within the engine control unitrare

How to diagnose

Read all stored codes and freeze frame data to see engine temperature, load and speed when the fault set, and note any other temperature or sensor circuit codes
Check coolant level and condition when the engine is cold, and look for signs of leaks or air in the system
Inspect the sensor connector and nearby wiring for corrosion, damage, chafing, heat damage and pin tension
View live data for the sensor with the engine running, wiggling the harness and connector to look for jumps or dropouts
Compare the head temperature reading with coolant temperature and intake temperature after a cold start; they should be close and rise sensibly
Check the sensor reference voltage and ground at the connector against the manufacturer's data for your model
Test the sensor resistance at different temperatures against the manufacturer's specification, and check the wiring for continuity and shorts
Clear the code and road test to confirm whether it returns, rechecking live data

How to fix

Clean, repair or replace the damaged connector terminals and secure the connector
Repair or replace damaged wiring, and re-secure the loom away from heat and rubbing points
Replace the cylinder head temperature sensor if it is faulty or erratic
Correct any reference or ground supply fault found in the shared circuit
Top up or refill and bleed the cooling system, and repair any leak found
Have the control unit checked and repaired or replaced only after all wiring and sensor faults are ruled out

Can I keep driving?

Medium severity

Short, careful journeys are usually possible, but get it checked soon as the control unit may be using a substitute value and engine protection or cooling control could be affected. Stop and investigate straight away if the temperature gauge rises abnormally or a coolant warning appears.

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