2009 Chevrolet P0118: What It Means & Is It Safe to Drive?
P0118 on the 2009 Chevrolet: Engine Coolant Temperature Circuit High Input. Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The engine coolant temperature (ECT) sensor is reporting a voltage signal that is too high, which the PCM interprets as an extremely cold or open-circuit condition. This is opposite to P0117 (low input) and often means the sensor or its wiring has failed open.
Common causes on the 2009 Chevrolet
- Failed engine coolant temperature sensor
- Open circuit in ECT sensor wiring
- Corroded or damaged sensor connector
- Low coolant level exposing the sensor
Symptoms
- Check Engine Light
- Engine runs rich (PCM thinks it is always cold)
- Poor fuel economy
- Hard starting when warm
Typical fixes
- Replace engine coolant temperature sensor
- Inspect and repair wiring and connector
- Check coolant level
Repair cost range
For a 2009 Chevrolet, repairs for P0118 typically fall between $50 and $200, depending on the root cause and labor rates in your area.
Known issues on Chevrolet
GM P0118 on Ecotec 2.4L and 1.4T engines typically means a failed ECT sensor or a wiring harness connector issue. The sensor on Ecotec engines is near the thermostat housing and is accessible; inspect the harness connector for corrosion.
Most commonly affected models