Hi, I’m new here and read a few posts on code p0118 but for different specifics than my Honda. My check engine light is on and I’m smelling coolant after a 20-30 min drive. I also see under the passenger side foot well what looks like coolant on the carpet? I’m not mechanically versed with this car and need some baby steps and simple instructions on these codes. I replaced the engine coolant temp sensor but the gauge sits at half way always. The engine seems to get really hot and fast with the car running rough to the point it’s going to die. Please help.

 

Are you planning on doing some of this work yourself? How long have you been driving with this leak? Have you added any coolant?

I would treat the P0118 & temp gauge in your car as one problem and the leak as completely separate problems. The leak is the most important as low coolant can overheat the engine and eventually will cause a head gasket failure. Replacing the head gasket is very expensive. It is possible your car was overheating the whole time and this is why your car is running rough.

For the leak: Since you smell and have coolant inside the car, you must make sure you radiator is topped off with coolant. When the engine is cold (sitting overnight or several hours turned off), remove the radiator cap and fill the radiator to the top with coolant. You can buy the 50/50 mix at the parts store. Water will work in a pinch, but water will freeze and cause damage when outside temperatures get below freezing. I recommend having a bottle or two of coolant in the trunk of your car. Search youtube on how to top off your radiator to find a good video.

To find the leak. Are you sure the liquid that is inside of your car is coolant? Use a paper towel to soak up the liquid to see if the liquid has the same tint as the coolant. Usually green or blue, but could also be orange. Look at the color in the plastic overflow tank near the radiator at the front of the car.

For P0118/gauge: This is an electrical fault for the coolant temperature sensor. Think of this sensor as a thermometer that sends an electrical signal to the engine computer that provides the coolant temperature. The computer then sends a signal to the gauge on your dash the temperature. The electrical problem could be a faulty sensor, some damage to the wiring to the sensor. Most likely replacing the sensor will fix this issue.