Faulty cylinder head temperature sensor (internal open circuit or drift); Damaged, corroded or loose sensor connector or terminals; Open circuit in the signal or return wire from damage, chafing or heat; Signal wire shorted to a voltage supply; Poor sensor ground or reference voltage fault at the control unit; Genuine overheating of the cylinder head from a cooling system fault; Fault inside the engine control unit.

P1289

Cylinder Head Temp Sensor High Input.

Other
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
2: AreaFuel and air metering (injector circuit)
89: FaultThe specific fault in that area

What it means

P1289 is read here as the generic-style definition 'Cylinder Head Temp Sensor High Input'. The engine control unit saw the cylinder head temperature sensor signal voltage above its expected range, which usually means an open circuit, a short to voltage or a failed sensor. Other makes use P1289 for completely different faults, so confirm the code definition for the specific vehicle before diagnosing.

Symptoms

Engine warning light on
Temperature gauge reading oddly, stuck or not moving (on models where the gauge uses this sensor)
Poor fuel economy or rough running
Hard starting or uneven idle, especially when warm
Cooling fan running constantly or at odd times
Reduced power if the engine enters a protective strategy

Possible causes

Faulty cylinder head temperature sensor (internal open circuit or drift)likely
Damaged, corroded or loose sensor connector or terminalslikely
Open circuit in the signal or return wire from damage, chafing or heatlikely
Signal wire shorted to a voltage supplypossible
Poor sensor ground or reference voltage fault at the control unitpossible
Genuine overheating of the cylinder head from a cooling system faultpossible
Fault inside the engine control unitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including engine temperature and coolant temperature at the time of the fault.
Inspect the sensor, its connector and the nearby wiring for damage, corrosion, heat damage, chafing or loose pins.
Compare the cylinder head temperature reading with the coolant temperature reading on a cold engine; they should be close. A very low or implausible reading suggests an open circuit or sensor fault.
With the engine cool, unplug the sensor and check the sensor resistance against the manufacturer's temperature table for that engine.
Check the signal, reference and ground at the connector with the ignition on, following the wiring diagram for the model.
Check the wiring for continuity between the sensor and control unit, and for shorts to voltage or ground.
Check the cooling system level, fan operation and thermostat to rule out genuine overheating.
Clear the code and road test, watching live data to confirm the reading rises smoothly as the engine warms.

How to fix

Replace the cylinder head temperature sensor if its resistance or live reading is out of specification.
Clean, repair or replace the connector and terminals if they are corroded or loose.
Repair or replace damaged wiring, including any open circuit or short to voltage.
Restore the sensor ground or reference supply if the fault is found there.
Repair any cooling system fault that is causing genuine overheating.
Replace or repair the engine control unit only after all wiring and sensor checks have been completed.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but get it checked soon because the engine may be running without proper temperature protection. Stop driving if the temperature gauge rises, a warning appears or the engine overheats.

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