Check Engine Light with Code P0117. Doesn't appear to be overheating, and temp gauge seems to be working fine.

[jamesbeat]

I was driving home this evening when my CEL came on. I stopped at Advance Auto and borrowed their meter. There was only one code set, and it was P0117, which is apparently the coolant temperature sensor reading too low a voltage.

My coolant level is fine, and the wiring to the sensor also appears fine from a visual inspection. The engine did not appear to be overheating, and the radiator hose felt warm, so I think the thermostat is working ok. Drivability seems unaffected, the engine seems to be running normally from what I can tell.

It seems that everything is pointing to a bad sensor, but wouldn't that also cause the temperature gauge to act weird? It's behaving perfectly normally; slowly moves to the center as the engine warms up and then stays there.

The sensor is cheap and easy to get to, so I have bought a replacement and will fit it tomorrow. I'm just wondering if there is anything else I should be looking out for? Can the temperature gauge still behave normally even with a bad sensor?

 

[LibertyTC]

Always best to replace with a Mopar Temp sensor.
I use an OBD2 scan gauge, as it can read the computer's current temp reading more accurately.

 

[derekj]

A partially stuck open thermostat can flag coolant temp codes - how long does it take for your engine to warm up when driving it in the morning? If it doesn't get up to temp in the time frame the ecm is looking for it will eventually flag a code.

 

[LibertyTC]

Yes if it takes too long to warm up, the code thrown would be too long to warm up.

 

[Ksat]

Might not hurt to take a resistance reading on the sensor and compare that to the new one you get, providing both have sat at the ambient temperature for a while, of course. When I took resistance readings on mine a while back, it was 8.13kohm @ ~80 degrees F and 0.8kohm fully warmed up.

 

[jamesbeat]

A partially stuck open thermostat can flag coolant temp codes - how long does it take for your engine to warm up when driving it in the morning? If it doesn't get up to temp in the time frame the ecm is looking for it will eventually flag a code.

That's interesting - I'm in Wisconsin, and it has been exceptionally cold lately. The wind chill has been as cold as -16, and I have noticed that it is taking longer for my engine to come up to normal operating temperature.

Can I safely rule out overheating as the cause? It seems unlikely that the temperature gauge in the instrument cluster would be behaving normally if the engine was overheating, right? I haven't noticed any steam coming from under the hood like one would expect if the engine was badly overheated.

Actually, does the temperature gauge get its information from this sensor, or is there a separate sensor for that?

 

[SXYFSH327]

Bad sensor? Just wondering the outcome...