P0118 on a Toyota: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive, but the engine may run rich and fuel economy will drop until the sensor circuit is repaired.

What P0118 means on a Toyota

On a Toyota, 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 ECT sensor on Toyotas rarely fails on its own, so an open wire or a disconnected connector is usually the real problem. While the code is active, the computer thinks the engine is always cold and adds extra fuel.

Is P0118 common on Toyotas?

P0118 is most common on higher-mileage Camry, Corolla, and RAV4 models, often after engine or cooling system work left a connector loose or a wire broken. It is a wiring fault, not an engine problem, and the sensor itself is a small, inexpensive part.

Commonly reported on: Camry, Corolla, RAV4, Tacoma.

Symptoms

Check engine light on
Poor fuel economy
Hard starting in cold weather
Engine runs rich with a fuel smell

Common causes

most common: Open sensor signal wire
common: Faulty coolant temperature sensor
common: Corroded or loose connector
less common: Sensor left unplugged after service

How to fix it

Fix	DIY?	Typical cost
Replace the coolant temperature sensor	Yes	$25–70
Repair the sensor wiring or connector	Mechanic	$50–150
Reconnect or replace the sensor connector	Yes	$20–50