P0117 on a Hyundai: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive for a short time, but the engine may run rich and burn extra fuel, and the cooling fan may run constantly.

What P0117 means on a Hyundai

On a Hyundai, P0117 means the engine coolant temperature (ECT) sensor is reading very hot because its voltage is too low. A failed sensor or a wiring short is the usual cause. The computer may run the engine rich and keep the cooling fan running.

Is P0117 common on Hyundais?

Elantras, Sonatas, Accents, and Tucsons see P0117 as the ECT sensor ages or its connector corrodes. It is a cheap, easy sensor fix and one of the more common coolant-related codes on higher-mileage Hyundais.

Commonly reported on: Elantra, Sonata, Accent, Tucson.

Symptoms

Check engine light on
Cooling fan runs constantly
Poor fuel economy from rich running
Hard starting when the engine is cold

Common causes

most common: Faulty coolant temperature sensor
common: Sensor wiring shorted to ground
common: Corroded or loose connector terminals
less common: Damaged wiring near the sensor

How to fix it

Fix	DIY?	Typical cost
Replace the coolant temperature sensor	Yes	$15–45
Repair the wiring or connector	Mechanic	$50–150
Have a shop replace the sensor and verify the circuit	Mechanic	$100–210