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. P017A is the general circuit fault without telling low from high. No manufacturer document using exactly this code was found: VW uses P017B/P017C/P017E for its sensor, and Ford's summaries list its own codes. Ford's published summaries still use its own codes P1289/P1290 for this sensor (fault below 0.244 V or above 4.96 V for 5 s). The description rests on CARB and component information. On a sensor fault the control module typically uses a modelled temperature and runs the radiator fan.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine light on
- Coolant temperature warning or wrong gauge reading
- Radiator fan runs loud or constantly
- Cold-start problems possible
Most likely causes
- Wiring or connector open or corroded
- Sensor faulty (moisture in the housing)
- Engine control module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It can trigger limp mode.
- It affects emissions.
What each character of P017A means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 1: Air and fuel
- 7A: Specific fault in that system
Frequently asked questions
Can I keep driving with code P017A?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P017A?
The most common causes are: wiring or connector open or corroded; sensor faulty (moisture in the housing); engine control module.
Related codes
- P017BCylinder Head Temperature Sensor A Range/Performance
- P017CCylinder Head Temperature Sensor A Circuit Low
- P017DCylinder Head Temperature Sensor A Circuit High
- P017ECylinder Head Temperature Sensor A Circuit Intermittent/Erratic
- P0115Engine Coolant Temperature Sensor 1 Circuit
- P0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.