# Engine light came on after putting in Thermostat



## Altiman93 (Nov 14, 2006)

check engine light is on. I put a thermostat in my car(i was running without one) and now that i installed one in, i did everything that i was supposed to do(red up on how to install thermo.)i loosend the bolt to let all the air out. i put collant in. and i drove it around and it warmed up cool! . But then i noticed that the Engine light came on. and wen ever i stopped at a red light the needle from being hot (needle was in the middle) to being cold(dropped all the way down as soon as i stopped) ..so now i have a new thermo. in with the engine light on and only warms up wen driving. if i let it idle the car goes back to cold...so im like ??!!
if anyone can help me i would appreciate it.
thanks for your time
-eG


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## mpe235 (Jan 19, 2009)

Check the connection to the coolant temperature sensor.


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## Altiman93 (Nov 14, 2006)

*...*



mpe235 said:


> Check the connection to the coolant temperature sensor.


i did. and the sensor is new i bought it 3 months ago wen i bought the car


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## Trippen (Feb 21, 2006)

With the cap off the radiator do you see the coolant moving as the car is running? Also when you did the bleed off and fill did you have the temperature selection switch in the car set to hot? If you didnt you could have a massive air pocket in the motor not allowing temp to be read correctly.


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## rogoman (Dec 16, 2004)

There are two temperature sensors side by side; the smaller one is for the temperature gauge; the larger one is for the ECU which may be causing the "check engine" light to come on. Make sure the harness connectors are secured.

You may have to do an ECU code readout to see what error code is being set.


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## Altiman93 (Nov 14, 2006)

it was the coolant temp sensor. its busted so i had to put tape to make sure its on their. but that problem is now gone. now my problem is that my car still runs cold and doesnt warm up at idle. it only warms up when i drive. but other than that it stays cold at idle


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## Altiman93 (Nov 14, 2006)

*yuppp*



Trippen said:


> With the cap off the radiator do you see the coolant moving as the car is running? Also when you did the bleed off and fill did you have the temperature selection switch in the car set to hot? If you didnt you could have a massive air pocket in the motor not allowing temp to be read correctly.


sure did put the heater on to full blast, and bled the system. and still runs cold at idle, but when im driving it warms up. and wen i stop at a red light it goes from being warm back down to being cold in a matter of minutes


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## rogoman (Dec 16, 2004)

I ran into the same type of problem some time ago. It turned out to be a defective thermostat. I made sure to install a Nissan OEM thermostat; not some aftermarket piece of junk.


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## Altiman93 (Nov 14, 2006)

so could it possibly be that i have a defective thermo? how much was the oem nissan one?


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## rogoman (Dec 16, 2004)

Could well be. An OEM thermo is around $20 - $30.


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## Trippen (Feb 21, 2006)

I had a STant Thermostat last month go bad been in the car for maybe 4months...But the weird thing is is started off bad....wasnt opening all the way...thought the temp was in the normal range...What keyed me into it my temp ws 180deg and it was 20's out side. So yes rogo might be correct in a bad thermostat


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## GLU49T (Feb 13, 2009)

take it to a mechanic just in case


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## Altiman93 (Nov 14, 2006)

first imma go to nissan and get a oem thermo. and hopefully it is a bad thermo. that i bought. thanks alot for your guy's help.


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## trmn8r (Apr 16, 2005)

Altiman93 said:


> first imma go to nissan and get a oem thermo. and hopefully it is a bad thermo. that i bought. thanks alot for your guy's help.


what i do is i use an infra red thrermometer and i measure the temperature on one side of the thermostate and then the other side of it and see if it opens when it hits its designated temperature. the two sides should even out in temperature when the thermostat opens. but ill take a guess at a bad thermostat even though its a new one.


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