Hello and ty for any help in advance. 2006 Explorer 4.0 EB. First off problem is coolant temperature will not go above 175 180*. New 2 CTS, new CTS housing at the same time. Test both new sensors and good resistance with temperature change. Test connections at CTS and PCM (Pin 18) both good and normal resistance from PCM connector to CTS connection. Scan tool CTS temp reading cold engine 75* KOEO and then KOER 75* and climbing to 175* winter or summer with AC running. Would like to be confident it’s my PCM. Has anyone used a rebuilder that is good. Sorry I forgot to say what thermostat is in it now a 195 stat.

 

Is the new sensor a Motorcraft or parts store brand?

 

It is a parts store brand. I did test it against the engine temperature and it was ok. Resistance follows water temperature.

 

Thermostat stuck open?

 

no the stat is ok. I have more than enough heat in the heater. I tested the heater lines and they were 180 190*. This has been going on for more than a year. I had this problem before I changed the thermostat housing but it had a 170* stat in it. I changed it for a 192* stat. Ty for your reply

 

After a good run, try using one of those hand held laser temp readers on the upper/lower coolant hoses.

It’s not possible to be running below 196° on a 90° day. Or even high 80’s. Not sure what your highest temps have been.

on a 88° day, waiting in a drive through, I’m hitting 206° coolant temps.