P017CCylinder Head Temperature Sensor A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Check engine light on
- Overheating or coolant warning despite a cold engine
- Radiator fan runs constantly
- Likely causes
- LikelyWater or coolant inside the sensor (O-ring damaged)
- PossibleSignal wire chafed against ground
- PossibleSensor shorted internally
- RareEngine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.