2005 Chevy Equinox cooling issues

Tiny
JNCFREEMAN
  • MEMBER
  • 2005 CHEVROLET EQUINOX
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 42,000 MILES
My engine service light keeps coming on. So I went and read my codes. It states "Coolant Temp below thermostat regulating temp". Initially the servicing was low, so I serviced it back up and pulled the battery to reset the computer. The light went out, but after a day and a half, it comes back on. I suspect the thermostat might be stuck closed, but wanted your input before I replaced it. Thanks in advance for your help.
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Thursday, March 18th, 2010 AT 1:14 PM

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Tiny
CARADIODOC
  • EXPERT
"the servicing was low, so I serviced it back up"

What does that mean? The code indicates the coolant isn't getting up to normal temperature in a certain amount of time. You might also be getting air from the heater that isn't as hot as normal. This would indicate a thermostat that is opening too soon or is stuck open.

When the engine isn't hot enough, fuel vaporizes poorly so some of it doesn't burn in the engine. This increases emissions and decreases fuel mileage.

To check this yourself, start the engine when it is cool and remove the radiator cap. Stick a thermometer in the coolant to measure its temperature when it starts to circulate. It should be around 190 degrees. If it is significantly lower, pinch the upper radiator hose for a minute, then see if the temperature goes up when you release the hose. If it does, suspect the thermostat.

If the coolant is already above 190 degrees, suspect the coolant temperature sensor.

Caradiodoc
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Thursday, March 18th, 2010 AT 8:03 PM
Tiny
JNCFREEMAN
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On this truck, it has the overflow tank that has a line that states "full line when cold". It was well below that line. So I added anti freeze to bring it up to the full line. On this truck, there is no Radiator cap to the actual radiator. It only has the cap to the overflow tank. I may be wrong, but I looked all over the top of the radiator. So do you want me to do the test from the overflow tank?
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Friday, March 19th, 2010 AT 1:08 PM
Tiny
CARADIODOC
  • EXPERT
Nope, lack of a radiator cap makes it impossible to measure the coolant temperature. What you can do is feel the upper radiator hose when the engine is warmed up, but that won't be very accurate. The hose should be too hot to hold onto for very long.

Your mechanic can connect a hand-held computer, called a scanner, to view sensor values. That will allow him to see what the coolant temperature sensor is reading and why it is setting that code.

Caradiodoc

caradiodoc
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Friday, March 19th, 2010 AT 1:43 PM

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