Cold Engine - Toyota Yaris Forums

Yoda · 03-14-2014, 08:15 AM

I have had this problem for about 8 months now. My cool engine light stays on no matter how long I drive. No CEL or anything related to it. My Scan gauge shows that the max temp it gets while cruising is 118F. If I am stuck in bad traffic and its a standstill, then it will rise to about 140F and the light goes off. When I get some speed it returns to 118F and cool light comes back on.

So my question is what would cause an engine to stay running cool even after an hour of highway driving?

Things I will be replacing are the Coolant temp sensor and the thermostat. That's all i can think of.

CTScott · 03-14-2014, 08:27 AM

Most likely it is just that the coolant temp sensor is bad.

bronsin · 03-14-2014, 08:48 AM

wouldn't that mess up the carburation?

CTScott · 03-14-2014, 09:10 AM

Quote:

Originally Posted by bronsin

wouldn't that mess up the carburation?

It would make the car run a bit rich, but if you keep driving with it that way the fuel trims will adjust it out.

Yoda · 03-14-2014, 09:11 AM

I am think so too CT. Easy to replace I will start there first. Maybe that's why its running so rough when its cold out.

bronsin · 03-14-2014, 09:40 AM

a yup.

jack black · 03-15-2014, 06:49 PM

Could it be thermostat stuck open? Is heater working OK or too cold?

Yoda · 03-19-2014, 07:18 AM

Heater is working fine but sometimes when the AC is on cold, it fluctuates between warm and cold.
Getting the temp sensor today to see if that works.

Bluevitz-rs · 03-20-2014, 08:22 AM

I'm voting bad thermostate.

Em_ · 03-24-2014, 08:46 AM

It's pretty dabgerous because if the fan ever needs to start and it doesnt you can damage your engine

Yoda · 03-24-2014, 08:57 AM

Have not had the time yet to do it. I will try for this weekend and let you guys know.

03-14-2014, 08:15 AM	#1
Yoda Drives: 2008 Black Sedan Join Date: Oct 2008 Location: FL Posts: 966	Cold Engine I have had this problem for about 8 months now. My cool engine light stays on no matter how long I drive. No CEL or anything related to it. My Scan gauge shows that the max temp it gets while cruising is 118F. If I am stuck in bad traffic and its a standstill, then it will rise to about 140F and the light goes off. When I get some speed it returns to 118F and cool light comes back on. So my question is what would cause an engine to stay running cool even after an hour of highway driving? Things I will be replacing are the Coolant temp sensor and the thermostat. That's all i can think of.

03-14-2014, 08:27 AM	#2
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Most likely it is just that the coolant temp sensor is bad. __________________

03-14-2014, 08:48 AM	#3
bronsin Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008 Location: nj Posts: 4,790	wouldn't that mess up the carburation? __________________ Synthetic Oil: Its All In Your Head

03-14-2014, 09:11 AM	#5
Yoda Drives: 2008 Black Sedan Join Date: Oct 2008 Location: FL Posts: 966	I am think so too CT. Easy to replace I will start there first. Maybe that's why its running so rough when its cold out. Last edited by Yoda; 03-14-2014 at 10:24 AM.

03-14-2014, 09:40 AM	#6
bronsin Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008 Location: nj Posts: 4,790	a yup. __________________ Synthetic Oil: Its All In Your Head

03-15-2014, 06:49 PM	#7
jack black Drives: 2007 red Yaris HB AT Join Date: Dec 2013 Location: southeast USA Posts: 197	Could it be thermostat stuck open? Is heater working OK or too cold?

03-19-2014, 07:18 AM	#8
Yoda Drives: 2008 Black Sedan Join Date: Oct 2008 Location: FL Posts: 966	Heater is working fine but sometimes when the AC is on cold, it fluctuates between warm and cold. Getting the temp sensor today to see if that works.

03-20-2014, 08:22 AM	#9
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	I'm voting bad thermostate.

03-24-2014, 08:46 AM	#10
Em_ Drives: 2007 Yaris Join Date: Jan 2012 Location: Laval, Canada Posts: 74	It's pretty dabgerous because if the fan ever needs to start and it doesnt you can damage your engine

03-24-2014, 08:57 AM	#11
Yoda Drives: 2008 Black Sedan Join Date: Oct 2008 Location: FL Posts: 966	Have not had the time yet to do it. I will try for this weekend and let you guys know.

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