P0118 on a Jeep: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive, but the engine may run rich and be hard to start in cold weather until the sensor circuit is repaired.

What P0118 means on a Jeep

On a Jeep, P0118 means the engine coolant temperature (ECT) sensor is sending a high-voltage signal that the computer reads as the engine being very cold. The sensor is usually threaded into the thermostat housing or cylinder head, and an open circuit from a failed sensor or broken wire is the typical cause. The computer then adds extra fuel as if the engine were cold.

Is P0118 common on Jeeps?

P0118 is most common on higher-mileage Wranglers and Grand Cherokees, including many with the 3.6L Pentastar engine. Dirt, moisture, and off-road use take a toll on the sensor connector, so corrosion is a frequent finding.

Commonly reported on: Wrangler, Grand Cherokee, Cherokee, Renegade.

Symptoms

Check engine light on
Poor fuel economy
Hard cold start
Engine runs rich

Common causes

most common: Faulty coolant temperature sensor
common: Open sensor signal wire
common: Corroded or damaged connector
less common: Wiring damaged by heat or rubbing

How to fix it

Fix	DIY?	Typical cost
Replace the coolant temperature sensor	Yes	$20–60
Repair the sensor wiring or connector	Mechanic	$50–150
Have a shop diagnose the circuit	Mechanic	$80–120