I think my truck is running too cold. Temp Gauge NEVER gets past O in Normal. Even on LONG trips. Today, after running the truck for about 40-60minutes, I popped the hood and felt the big hose to the radiator. It's warm but not hot. Also, the radiator cap is just warm. You can leave your hand on both things since they're not hot.

Did a Test this morning and the ECT failed on both KOEO and KOER. I warmed up the engine nice and good, and this time, it passed KOEO, but failed KOER. I went out and got a digital multi-meter since my old one crapped out. What are some readings that ECT should have?

Now, on the thermostat. Can that be checked with voltmeter? I know its a really cheap part, so I might just get a new one. Where exactly is the t-stat?

When removing either ECT or T-stat, will Coolant leak out.

I think this is causing my truck to run rich. Computer thinks it's cold all the time and then enriches it too much...which also throws code 42 during KOER.

 

It might be worthwhile to figure out the exact temperature that your engine is running, since most Ford trucks I have seen run around the O in normal at normal operating temperature.

A Haynes manual will have resistance values for the ECT at various temperatures - I can't remember them right off the top of my head. A lower than expected coolant temperature can cause the ECT code to be thrown, even though the sensor itself is fine.

The thermostat is a mechanical device and cannot be checked with a volt meter. You must take it out to test it, and by that time it might be just as easy to put in a new one. The thermostat is behind the metal neck where the top radiator hose connects to the engine.

If you should remove the thermostat housing or the ECT, coolant will certainly leak out. What you can do is drain a little bit from the drain petcock on the bottom of the radiator to get the water level down to below the thermostat - this will lessen the amount of water that spills.

 

I checked fordfuelinjection.com....they have values for ECT. I'll test ECT tomorrow. I think I'll drop in a new thermostat as well. Temp Gauge gets barely to the 'C' and MAYBE can get to the N.