Hello everybody. I'm a new 2002 X-Type 2.5 owner as of Wednesday of this week, and I really hate for my first post to be about a problem.

Last night, I was driving the car home when about 10 minutes into my drive, the car threw a P0128 code - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

So I clear it with my handheld, thinking that if it comes back, I'll replace the thermostat. Well, all is good until my drive home tonight. Same situation, roughly 10 minutes after I start the car, a code gets thrown. But this time it's P0116 - Engine Coolant Temperature Circuit Range/Performance Problem. I knew that the car was not in fact over heating, so I cleared the code again and continued home.

The day after I picked it up, I took it to an express center to get the oil changed. They also topped off the fluids. I'm guessing that whatever coolant that they topped it off with didn't match. Could this be the problem? Of course, the previous owner says that he has not had any problems like this in the past. So, I want to be sure that the thermostat and hose will fix it before I spring $115 for one.

ECT sensor?
Thermostat?
Bad mix/match of coolant?
Thoughts?

 

Thermostat

 

The same thing happened to me. I've gotten the p0128 code a few times and have cleared it but it keeps coming back every couple days (Along with p1000 and N/A). So I ordered the thermostat and hose assembly this week, and I go to clear the code this morning and now it has those three codes and one more now, p0116. I was hoping to get the thermostat in the mail today so I could work on it this weekend but maybe tomorrow it will get here. This coolant things been real annoying. First the coolant tank broke. I ordered a new one, waited a week, replaced it and flushed it (added some stop-leak stupidly for no reason). 2 weeks go by and it's fine, no codes or anything. Then I put some Sea Foam in the gas tank and those check engine lights start popping up for my thermostat!? So I'm guessing it's unrelated but it looks like my thermostat is shot, so I opted for the new hose assembly. Will be glad when this coolant stuff gets sorted out.

 

X2 on the thermostat. Mixing coolant won't give you any of those types of problems.

The thermostat is either plugged with a piece of trash like old gasket or chunk of rust, or spring is fatigued, either way it's a cheap part to fix.

Good luck!

 

I'm going to do that, I am just waiting on the part. Thought it would be here by this weekend but they must've lagged on the shipping. Looks like a big project but hopefully it will get it taken care of. So there's no need for a gasket sealant or anything when you install the new thermostat? I just bought the thermostat and hose assembly. It didn't mention anything about needing a gasket and it sounds like you just bolt it in. Wondering if it includes a gasket on the thermostat.

 

I'm gonna be trying to change out the thermostat and top radiator hose this weekend. Any last minute pointers? Hoping it gets rid of the check engine light.