Coolant Temp Can't Make Up It's Mind

[Meeks726]

Hello everyone, fairly new here in the forum and not really sure if I'm in the correct section or not but....

Recently, my CEL came on and read "P0126". My car wasn't fully warming up. Temp would stay at around 140 - 159 ish driving in town or the highway.
After doing some research, I decided to replace the THERMOSTAT.

The first time I replaced the Thermostat, I replaced it with one from AutoZone.
CEL went away but coolant temp were still around 140-159 after letting the car idle and after driving it around town and on the highway.
Since the coolant temps were still 140-159, I figured that maybe it's a faulty Tstat or AutoZone's is just shit. So I bought an OEM one from EdgeAutoSport.

The second time I replaced the Thermostat, I replaced it with an OEM one from EdgeAutoSport. CEL still didn't come back but the coolant temps were still around 140-159.
I let the car idle for about an hour with AC on full blast and then Heater on full blast, coolant temp still didn't go past 159~.
So I decided to take the car out for a drive around town and do some pulls on the highway.
When I got on the highway, I did a 3rd to 4th pull and suddenly, my coolant temp went back to normal after hitting 21psi of boost.... After that pull, my coolant temps were around 175-189 on the highway and 189-217 around town doing stop-and-go.
When I got home, I let the car idle for about 20 mins and the coolant temp stayed at around 210-217 and then I called it a night.
Btw, the fan does come on whenever temp reaches 217 or 219.

The next day, the car started fine and the coolant temps were fine. The car reached operational temp normally. When I got to the highway, I ripped the car again from 3rd to 4th and the coolant temp went back down to 144-159.... then I ripped it again and it went back up to normal... it seems to change back and forth every time I get on it or every time I hit full boost...??
So the car's coolant temp range seem to change whenever I do WOT pulls or hit high boost....???
Anyone have any ideas???

[Vansquish]

Originally Posted by Meeks726 Hello everyone, fairly new here in the forum and not really sure if I'm in the correct section or not but.... Recently, my CEL came on and read "P0126". My car wasn't fully warming up. Temp would stay at around 140 - 159 ish driving in town or the highway. After doing some research, I decided to replace the THERMOSTAT. The first time I replaced the Thermostat, I replaced it with one from AutoZone. CEL went away but coolant temp were still around 140-159 after letting the car idle and after driving it around town and on the highway. Since the coolant temps were still 140-159, I figured that maybe it's a faulty Tstat or AutoZone's is just shit. So I bought an OEM one from EdgeAutoSport. The second time I replaced the Thermostat, I replaced it with an OEM one from EdgeAutoSport. CEL still didn't come back but the coolant temps were still around 140-159. I let the car idle for about an hour with AC on full blast and then Heater on full blast, coolant temp still didn't go past 159~. So I decided to take the car out for a drive around town and do some pulls on the highway. When I got on the highway, I did a 3rd to 4th pull and suddenly, my coolant temp went back to normal after hitting 21psi of boost.... After that pull, my coolant temps were around 175-189 on the highway and 189-217 around town doing stop-and-go. When I got home, I let the car idle for about 20 mins and the coolant temp stayed at around 210-217 and then I called it a night. Btw, the fan does come on whenever temp reaches 217 or 219. The next day, the car started fine and the coolant temps were fine. The car reached operational temp normally. When I got to the highway, I ripped the car again from 3rd to 4th and the coolant temp went back down to 144-159.... then I ripped it again and it went back up to normal... it seems to change back and forth every time I get on it or every time I hit full boost...?? So the car's coolant temp range seem to change whenever I do WOT pulls or hit high boost....??? Anyone have any ideas???

Sounds like you might not have burped the system fully.

[Fstrnyou]

I would lean more towards an electrical issue. Possibly the sensor or the sensor connection.

[Meeks726]

Okay so I was driving my car today for about 2 hours rippin through gears and coolant temp stayed normal....... BUT CEL P0126 came back on...??

[Fstrnyou]

Replace temp sensor/switch. A loose connection would cause the temps to swing from actual to max cold/hot instead of just reading inaccurately.
The sensor is probably fairly cheap and I believe it's easy to reach.

[Meeks726]

Originally Posted by Fstrnyou Replace temp sensor/switch. A loose connection would cause the temps to swing from actual to max cold/hot instead of just reading inaccurately. The sensor is probably fairly cheap and I believe it's easy to reach.

Would you be kind enough to direct me to a "How-To: Coolant Temp Sensor"? I can't seem to find it here or youtube

[Fstrnyou]

I google searched and it was the first link to pop up.

[MSMS3]

Originally Posted by Meeks726 Would you be kind enough to direct me to a "How-To: Coolant Temp Sensor"? I can't seem to find it here or youtube

Come on, sir. At least try. What terms did you search? We get frustrated looking up stuff for people who should be able to find stuff. Not trying to be a hard ass, but trying to break people from tit sucking and eat real food with a fork, knife and spoon. Search is your utensil.

[Meeks726]

Originally Posted by MSMS3 Come on, sir. At least try. What terms did you search? We get frustrated looking up stuff for people who should be able to find stuff. Not trying to be a hard ass, but trying to break people from tit sucking and eat real food with a fork, knife and spoon. Search is your utensil.

Well sir damn I'm sorry

Originally Posted by Fstrnyou I google searched and it was the first link to pop up.

I didn't find a legit "How-To" but I found a thread showing where it's located. I'll give it a try tomorrow. Thanks