Powertrain, generic · Fuel and air metering

P017C Cylinder Head Temperature Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The cylinder head temperature sensor A is an NTC thermistor that measures the temperature of the cylinder head metal or of the coolant in the head. Some Ford engines use it instead of a coolant temperature sensor and calculate a coolant value from it; VW group V8 petrol engines use it as sender G407. CARB requires such sensors to be monitored like the coolant sensor. P017C means the signal voltage is too low – a short to ground of the signal wire or a short inside the sensor; the control module would read an implausibly hot cylinder head. 'Low' refers to the signal, not the temperature. Audi and Bentley document it as a short to ground, most often caused by water inside sender G407 after O-ring damage. Ford flags the same condition on its own code below 0.244 V for 5 s. A substitute value is used; an overheating warning with a cold engine is a typical sign.

Likely causes

Water or coolant inside the sensor (O-ring damaged)
Signal wire chafed against ground
Sensor shorted internally
Engine control module

Symptoms

  • Check engine light on
  • Overheating or coolant warning despite a cold engine
  • Radiator fan runs constantly

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cylinder head temperature sensorsensor wiringcooling system

Related codes

P017AP017BP017DP017EP0117

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, newtonnet.co.uk.