Open circuit or poor connection in the sensor wiring or connector, such as corrosion or a pushed-out terminal; Faulty cylinder head temperature sensor reading falsely cold or out of range; Damaged wiring harness with a short to voltage or a break, often from heat or chafing; Sensor signal or reference circuit shorted to another supply; Poor ground or reference supply fault shared with other sensors; Fault inside the engine control unit.

P017D

Cylinder Head Temperature Sensor A Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
7D: FaultThe specific fault in that area

What it means

P017D means the engine control unit has detected a high voltage signal in the circuit of cylinder head temperature sensor A. The signal is higher than the normal operating range, which usually points to an open circuit, a short to voltage or a failed sensor. Not every engine has a cylinder head temperature sensor, and the exact location and wiring depend on the model and engine.

Symptoms

Engine warning light on
Engine running in a reduced power or limp mode
Poor or uneven performance, especially when hot
Temperature gauge reading oddly, if it uses this signal
Rough running or hard starting on some engines
Cooling fan running constantly on some models

Possible causes

Open circuit or poor connection in the sensor wiring or connector, such as corrosion or a pushed-out terminallikely
Faulty cylinder head temperature sensor reading falsely cold or out of rangelikely
Damaged wiring harness with a short to voltage or a break, often from heat or chafingpossible
Sensor signal or reference circuit shorted to another supplypossible
Poor ground or reference supply fault shared with other sensorspossible
Fault inside the engine control unitrare

How to diagnose

Read all stored codes and freeze frame data, and note whether other temperature or sensor supply codes are present.
Compare the live cylinder head temperature reading with coolant temperature on a cold engine; they should be close.
Visually inspect the sensor, connector and harness for damage, heat marks, chafing, corrosion and loose terminals.
Check the live data while gently wiggling the connector and harness to see if the reading jumps or drops out.
Unplug the sensor and check the live reading and the voltage at the connector against the manufacturer's specification.
Test the sensor resistance at different temperatures against the model-specific values.
Check the sensor circuit for continuity, short to voltage and short to ground, plus the sensor ground.
If the wiring and sensor are good, check the control unit supply, grounds and any applicable service information before suspecting the unit.

How to fix

Clean, repair or replace the damaged connector or terminals.
Replace the cylinder head temperature sensor if it is out of specification.
Repair or replace the damaged wiring, correcting any open circuit or short to voltage.
Restore faulty sensor ground or reference supply connections.
Replace or repair the engine control unit only after all other causes are ruled out and as the manufacturer advises.

Can I keep driving?

Medium severity

The car can usually be driven short distances, but the engine may be in a protective mode and the control unit cannot properly monitor head temperature. Get it checked soon, and stop if the temperature gauge rises or a coolant warning shows.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.