Engine

P017D — Cylinder Head Temperature Sensor A Circuit High

Severity: medium Drive with care, to a shop

What P017D means

The engine control module (ECM) detected a voltage that is too high in the cylinder head temperature (CHT) sensor A circuit. The sensor is a thermistor whose resistance changes with heat, and the ECM reads the voltage drop across it to estimate cylinder head temperature. High voltage usually points to an open circuit, a poor connection or a signal wire shorted to voltage.

Symptoms

  • Check Engine light is on
  • Rough idle or misfire in some cases
  • Hesitation or intermittent performance problems
  • Incorrect temperature readings or signs of overheating
  • Higher fuel consumption from a fallback control strategy

Possible causes

  1. Failed cylinder head temperature sensor (internal open circuit)
  2. Open signal or ground wire in the sensor circuit
  3. Signal wire shorted to voltage
  4. Corroded or loose sensor connector
  5. Damaged wiring harness near hot engine parts
  6. ECM fault or software issue (uncommon)

How to diagnose

  1. Scan for codes and review freeze frame data, then clear the code and see if it returns
  2. Compare CHT and coolant temperature readings on a cold engine; they should be close
  3. Inspect the sensor connector and harness for heat damage, chafing, corrosion or moisture
  4. Unplug the sensor and check for reference voltage (typically about 5 V) and ground per the factory wiring diagram
  5. Measure sensor resistance and compare it to the spec for the current temperature
  6. Test the wiring to the ECM for opens and shorts to voltage
  7. If the sensor and wiring are good, check the ECM and look for software updates

Common fixes

  • Replace the cylinder head temperature sensor
  • Repair damaged wiring, replace the connector or clean the terminals
  • Update ECM software or replace the ECM if the sensor and wiring test good

Questions and answers

What does code P017D mean?

It means the ECM sees high voltage in the cylinder head temperature sensor A circuit. The usual causes are a bad sensor, an open wire or a poor connector contact.

Can I drive with P017D?

Short trips are often possible, but the ECM lacks accurate head temperature data and may not protect the engine from overheating. Watch the temp gauge and get it diagnosed soon.

How do I fix P017D?

Start by inspecting the connector and wiring, then test the sensor with a multimeter. Replacing the sensor or repairing the wiring fixes most cases.

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.