I keep getting a service engine soon code on my 2001 blazer, the code is for the coolant temperature sensor. I replaced it, but still the code came back. Could it be something else like the thermostat maybe, where is the thermostat located? Just wondering if anyone else has had this problem, thanks.

 

What is the code?

Do you have a temperature gauge in the dash? If so, what is the temperature indicated?

If you follow the upper radiator hose (driver side top of the radiator) to the engine, the thermostat will be at the opposite end. The thermostat housing is located right in front of the throttle body.

 

Hey man I just went thru this myself, It would help if you posted the code I think mine was p0128 so I did some research and replaced the t-stat and cleared it up. Watch your temp gauge if it never comes up to full operating temp its probably a stuck open t-stat, although I read whenever the ECM sends this code the comp puts the cooling fan on all the time (I guess the rational is an engine running too cold is better than one running too hot). Until you clear the problem you may notice some decreased fuel economy as the motor is running cold. At the same time from internet reading I topped up my coolent to the "full hot" mark when cold and replaced the rad cap (with a quality unit not OEM, stant i believe). Why?.... apparently ambient air and dexcool dont get a long well, both a poor sealing rad cap and lower overflow levels will allow some air to enter the cooling system and begin an ugly process leading to costly repairs (search dexcool and brown sludge and you'll be well informed). A new rad cap and anti-freeze top up is pretty cheap insurance if you ask me.

Also when removing the t-stat be advised you will spill a considerable amount down the side of the engine as you remove it, the only way to avoid this is to remove some from a drain valve on the bottom (passenger side?) of the rad. Once you reinstall the t-stat remember to fill your coolent system back up fully with dexcool to avoid air pockets. Thru more reading when it came time to top it up I drove the truck up on ramps (a hil would work too) let her get warm and kept topping it back up when the level in the rad would drop, held rpms steady at 1500 and kept topping up, gave the chassis a few shakes and topped her up again until i was satisfied that I had all the air out of the system.

Now for the disclaimer: I am no way a mechanic or tech and am only speaking from personal experience with my vehicles, Hopefully one of the real tech's will vouch for this information or disclaim it, either way you'll know what to do!!! Good luck