2003 coolant Temp Sensor

[sdaffer]

I did a search but was unable to find an answer. My service engine light came on today so I went to the autoparts store and had them check the code. It returned the code for the coolant temp sensor. The parts guy said it could possibly be a bad connection if not the sensor needs to be replaced. I found the sensor and where it connects but I can't figure out how to get the connector apart to check the connection. Can someone give me some pointers?

Thanks

[Jozuah]

I did a search but was unable to find an answer. My service engine light came on today so I went to the autoparts store and had them check the code. It returned the code for the coolant temp sensor. The parts guy said it could possibly be a bad connection if not the sensor needs to be replaced. I found the sensor and where it connects but I can't figure out how to get the connector apart to check the connection. Can someone give me some pointers?

Thanks
Welcome to trailvoy!!
please start by filling in your profile with your vehicle info under User CP. this will allow us to give you the best advice we can !!

what was the exact code?

MANY of us including myself have had the CTS be too low and needed to replace the thermostat. the issues with mine have been solved since replacing the T-stat.

to determine the real cause we need the exact code thats been set, from there we can further assist you with your problem.
Josh

[tblazed]

I found the sensor and where it connects but I can't figure out how to get the connector apart to check the connection. Can someone give me some pointers?

Thanks


If it's the type of connector I think it is, you pull out the gray locking part about half-way, then press in the center black plastic part of the plug, it will give a little to release, while you pull and unplug it.

[sparky24w]

hi everybody, i have a 2003 gmc envoy, and i had the chek engine light come on it was the code p0128 so i went to autozone bought a t-stat and a coolant temp sensor replaced the t-stat and the cts and now my envoy cant even stay idled. can someone please tell me what i might of done wrong.

[WOOLUF1952]

hi everybody, i have a 2003 gmc envoy, and i had the chek engine light come on it was the code p0128 so i went to autozone bought a t-stat and a coolant temp sensor replaced the t-stat and the cts and now my envoy cant even stay idled. can someone please tell me what i might of done wrong.


What year and how many miles?

When you changed the parts, did you disconnect the battery?

If you did, the PCM was reset to factory settings. You probably need to clean your throttle body.

[sparky24w]

yes i did disconnect the battery, my envoy ran fine until i changed the cts on it it just doesnt want stay idled i have 97,000 miles on it.

[christo829]

Bets are on needing a throttle body clean, as Wooluf1952 said.

At 97K, if you've never done it or had it done, there's a lot
of buildup behind the butterfly valve in the throttle body.
Over time, the PCM learns to compensate for that buildup.

When you disconnected the battery, the PCM lost those
learned parameters, and defaults to either no parameters or
to assuming a clean throttle body. Either way, those parameters
won't work with a dirty throttle body.

Here's the How-to:

http://forums.trailvoy.com/articles.php?do=viewarticle&artid=91

Definitely use a throttle body cleaner or something else that's
listed as safe for downstream sensors and plastics.

Also, even though you've already done it, you should probably
disconnect the battery while you clean in order to *re*-reset
the PCM, and also to avoid possibly damaging the actuator motor
if you accidentally push the butterfly while the unit is energized.

Good Luck!

Chris

[sparky24w]

thanx guys i appreciate all your input my envoy runs like a brand new truck cant even hear the truck idle once again thank you that replied.:)

[barniejekyl]

it's great the help we find on this site......cheers c(__) []

[jcjarhead]

Hi:

I too saw my SES light come on this weekend and went to Autozone today and it says "coolant temp below thermostat"....

My truck is on the way to having a third fan clutch installed soon...it has been "whinning" for about a month...is there any possibility I am getting this code due to the dreaded fan clutch issues? I ask because my temp guage is exactly two clicks (small ones) before mid point (ideal if I have read some here correctly).

Also...does the PCM in any way interact with the fan clutch? I ask because the most recent fc only lasted 6 months and was loud from install on....I think it may be defective and am trying to deal with Rock Auto where I purchased it. A dorman unit made in Korea.

Can some of you more techncal folks advise me please. I love the truck but this fan clutch issue really stinks! Thanks in advance!

[jcjarhead]

Meant to add....I did just change the battery out (probably a month ago)...so it likely factory reset....but should that effect the fan clutch? As stated...it seems to have been loud since install...which was before I changed the battery to an Optima. I am at 90k miles in case that helps?

[jcjarhead]

Hi:

Doesnt seem to be many technical folks on here of late willing to answer questions?

Maybe I am doing something wrong here and no one is telling me? Maybe thats why I dont often get replies? Sorry if I am somehow in "violation"...its my ignorance...not on purpose whatever it may be?

If anyone happens upon this...and can respond...it would be most appreciated.

Does anyone know what involvement the PCM has with the fan clutch..if any...had it replaced and it still sounds loud...could it be PCM related or defective part?

[christo829]

Two clicks below sounds too cold. Mine is currently running one
click below, and I'm cycling between 176 and 186 degrees when I
watch the real time data stream. Your P0128 is most likely the
thermostat. Mine hasn't thrown a code yet, but it sounds like
you're running colder than mine. Do you have access to a scan tool
that can read real time data?

The PCM does communicate with the fan clutch, as far as telling
the fan what speed it wants to see based on the temperature and
then looking at what speed the fan is actually reporting.

Your fan clutch *could* be faulty, but is that the original thermostat
in your truck? 90k miles is long enough that the thermostat could
have gotten tired, and with that many miles, could probably stand
replacing anyway.

That's the cheaper route as well... ;)

Good Luck!

Chris

[jcjarhead]

THANKS CHRIS....I am going to take your advice and do t-stat for sure.

I did actually buy another fc and will likely have it installed too. I almost wonder if I got a defective one (Dorman from China)? As the one before it...the noise did go away and the fc did perform for about 18 months.

Looks like I may have two issues? I am going to give teh t-stat a shot myself based on the how to here....The fc....I am a bit more leary about?

I may even do the PCM4less tune I see on here too and perhaps I can get the PCM upgrades I need...do you remember the GM site where you put in vin number to find out?

[jcjarhead]

Can someone please confrim that the above GM part number is infact the thermostat and not just the "housing?"

MUCH THANKS IN ADVANCE!