Engine

P017E — Cylinder Head Temperature Sensor Signal Erratic

Severity: medium Drive with care, to a shop

What P017E means

The engine computer is receiving a signal from the cylinder head temperature (CHT) sensor that drops out or jumps around more than real temperature could change. The sensor is normally a thermistor whose resistance shifts with heat, letting the computer read the temperature of the cylinder head metal. That data helps protect the engine from overheating and supports engine control.

Symptoms

  • Check Engine light is on
  • CHT readings jump around or drop out on a scan tool
  • Rough idle
  • Reduced power or limp mode
  • Overheat warning on some vehicles

Possible causes

  1. Failed cylinder head temperature sensor
  2. Damaged, chafed or intermittent sensor wiring
  3. Corroded or loose connector terminals
  4. Poor ground or reference voltage supply to the sensor
  5. Rarely, a fault in the computer's input circuit

How to diagnose

  1. Scan all codes and freeze-frame data, noting any other temperature or sensor supply codes
  2. Watch live CHT data on a cold and warm engine and note any spikes or dropouts
  3. Inspect the sensor connector and harness for oil, corrosion, rubbing or a loose fit
  4. Wiggle the harness and connector with the engine running while watching the data
  5. Check reference voltage and ground at the sensor connector with a multimeter
  6. Measure sensor resistance and compare it to the factory spec at that temperature
  7. Test the wire from the sensor to the computer for opens and shorts
  8. If wiring and sensor are good, check the computer and its connectors

Common fixes

  • Replace the cylinder head temperature sensor
  • Repair the wiring harness or damaged wires
  • Clean or replace corroded terminals and the connector
  • Restore the sensor ground or supply circuit
  • As a last resort, reprogram or replace the engine computer

Questions and answers

What does P017E mean?

It means the signal from the cylinder head temperature sensor is unstable, dropping out or jumping suddenly. The cause is most often the sensor itself or its wiring.

Can I drive with P017E?

Short trips are usually possible if you watch engine temperature closely. If you see signs of overheating or lose power, stop and get it fixed.

How do I tell a bad sensor from a bad connection?

Wiggle the harness and connector with the engine running while watching the scan tool data. If readings jump when the wiring moves, it's a connection or wire problem; if not, test the sensor itself.

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.