Hello all,
I got in my car yesterday and the lovely check engine light was on my 2011 CS. When I got home I plugged in the scanner got the code and started researching. Okay, thermostat housing needs to be replaced and from what I read the water pipe should be replaced at the same time. I went to pick up my daughter and plugged in the scanner to monitor the temperature. The coolant temp bounced between 225 and 231 while driving for about 30 min. When I got home and let the car idle the temp held at 231. Does this seem like a stuck open thermostat housing?

I should mention, the day before I was siting in the car and heard what sounded like fluid rushing through a pipe behind the radio and lower right side dash.

Thank you for all your help.

 

What version t-stat is on your car? Does it have the other sensor in the coolant pipe? The t-stat is 105C (221F) so 225 is about normal, but 231 is a bit high in my experience depending on ambient temp and whether the AC was on or not. When was the coolant changed last? Are you losing any coolant?

All signs point to replacing the t-stat housing and do a coolant change. The part isn't that expensive and is a reasonably easy DIY.

 

https://www.pelicanparts.com/More_In...YaAs9iEALw_wcB

This is the housing I ordered. The ambient temp yesterday was 90f today was 75f and the coolant temps remained the same. I did not notice a difference when I turned in the AC.

I ordered the housing, connectors, and water pipe. Looks like I am going to have a fun Thursday, when the parts arrive.

 

Good stuff, does your elbow coolant hose in the front have a sensor built into it? If so, you should replace that hose as well.

I have done the t-stat housing job several times now and I haven't replaced the plastic coolant pipe in the rear across to the water pump. It is a pain and I only replace it if it is leaking. Some may disagree with me, but if things aren't leaking on this car, I leave it alone.