P0118 on a Honda: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive, but the engine may run rich and idle roughly until the sensor circuit is repaired.

What P0118 means on a Honda

On a Honda, 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 sits near the thermostat housing, and Honda connectors are known for corrosion that opens the circuit. Note that Honda uses a separate sensor for the dashboard gauge, so the gauge can read normally while this code is set.

Is P0118 common on Hondas?

P0118 is common on higher-mileage Civic, Accord, and CR-V models. Corroded connectors and broken wires at the sensor are the usual findings, and a loose connector after timing belt or water pump service is a frequent surprise.

Commonly reported on: Civic, Accord, CR-V, Pilot.

Symptoms

Check engine light on
Poor fuel economy
Rough idle or hard cold start
Exhaust smelling rich

Common causes

most common: Faulty coolant temperature sensor
common: Corroded sensor connector
common: Open sensor signal wire
less common: Loose connector after engine service

How to fix it

Fix	DIY?	Typical cost
Replace the coolant temperature sensor	Yes	$25–60
Clean or replace the corroded connector	Yes	$20–50
Repair the sensor wiring	Mechanic	$50–150

Frequently asked questions

Can I drive my Honda with a P0118 code?

Yes. The engine will run rich and may idle roughly, but it is not an emergency. Fix the circuit soon to restore fuel economy.

Why does P0118 happen on Hondas?

Honda connectors are prone to corrosion, so a corroded or open sensor circuit is the usual cause. The gauge stays normal because Honda uses a separate gauge sensor.

How much does it cost to fix P0118 on a Honda?

A replacement sensor is about $25 to $60, plus labor if a shop does it. Cleaning a corroded connector is cheap if you do it yourself.