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2004 chevy trailblazer_ls_ext
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Discussion Starter · #1 ·
Hello all. I am new to this forum and I look forward to discussing our trailblazers with all of you. Right now though I have a small problem. I have a 2004 EXT with a 6cyl engine and it wont pass smog:sadcry:. I have been recently laid off from my job:sadcry:,and my wife only works part time:sadcry:. I live in Henderson, Nevada and the code from the smog place is "P0128 COOLANT TEMPERATURE(COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMP)" I really don't have the money for repairs and my registration expires on 7/13/09. If anyone has any advice I would greatly appreciate it.

Thanks All,:)

NEVPAT
 

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2005 chevy trailblazer_ls
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:tiphatHello and welcome to the site...according to OBD II .com...low coolant..leaking or stuck open t-stat...faulty coolant fan(run too much)...faulty coolant temp(ECT) sensor...faulty intake air temp(IAI) sensor. I hope this helps:thumbsup:
 

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2004 gmc
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If your temp gauge is reading less than straight up 210 degrees, it's almost certainly just the thermostat. Search for a thread on how to replace it. Assume you've got tools, since you sure have the motivation. Good luck and welcome! :tiphat
 

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2006 chevy trailblazer_ls
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I'm gonna say that it's most likely a thermostat... but possibly the coolant temp sensor saying the temp's too low... go with everybody else and replace the t-stat since it's ridiculously cheap and see if that solves your problem.
 

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2003 gmc envoy_slt
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:tiphat Welcome :tiphat .As roadie stated, if the gauge is reading below the 210 mark, it is most likely the t-stat. Around here they're about $25 + tax. They are a PITA to change, but looking on the bright side, you now have the time to replace it.:m2:
 

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Discussion Starter · #8 ·
Thanks!

If your temp gauge is reading less than straight up 210 degrees, it's almost certainly just the thermostat. Search for a thread on how to replace it. Assume you've got tools, since you sure have the motivation. Good luck and welcome! :tiphat
Actually it would probably be important to say that the temp gauge is perfect and I have had the same check engine light on for about a year now. The last time it came on it was just a bad sensor and I was not about to spend the money again on a bad sensor. Thanks again!
nevpat:)
 

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2004 gmc
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...The last time it came on it was just a bad sensor and I was not about to spend the money again on a bad sensor....
If only you had taken it seriously when the light came on, it wouldn't be like a last minute thing. Last minute troubleshooting seems to always come with angst and drama and expense. Where have you been the last year if not on trailvoy? ;)

Don't you HAVE to spend the money to fix the issue? You can't pass inspection otherwise?

If you know somebody with a scan tool that can look at the data from the sensor, you can see if it's telling the truth. But from what we see usually, a bad sensor will put the gauge somewhere other than at 210. A bad thermostat will keep the fluid temp low, but the PCM is constantly filtering the sensor data and trying its best to lie to you and put the gauge needle at 210, even if the fluid temp is 180-185. So statistics lead us to believe it's more likely to be the thermostat then the sensor.

But we're just an internet forum. We're not mechanics touching your car physically with the right diagnostic equipment.

If you're not able to change the thermostat with the instructions given in other threads, it's not like we can change our advice, either. Sorry.
 

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Discussion Starter · #10 ·
Sooorrrrrrrryyyyyyy!

Gosh! I never thought I would get lectured on a forum for asking a question!:eek: I really enjoy my trailblazer but it always seems to have a sensor issue. In todays world no one has any honor anymore. Mechanics will rape you because these machines are so sophisticated. The government rapes you with the smog in the first place! I am somewhat machanically inclined since I grew up around cars and mechanics. Today you need an analyzer to troubleshoot computerized systems and I know there are a lot of knowledgable people out there who are willing to share their knowledge so we are not completely dependent upon mechanics to rip us off! So thanks all who offered their knowledge, I really appreciate it and I look foreward to further discussion.:thx
 

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I wasn't cranky about your asking a question. Not at all. I reacted poorly to the additional information you shared in post #8 that would have been much more efficient if you'd told us the background all at once. And then you said you weren't about to spend money again on a bad sensor. My philosophy is that a bad sensor needs to be replaced ASAP. Check engine lights get dealt with immediately. It sounded like you thought it was a waste to replace a bad sensor, or that looking into why a Check Engine Light comes on is an optional thing that can be deferred for a year until you're forced to deal with it to pass smog. As you noted, these are technologically advanced, sensor-driven vehicles, and one way to save money in the long run is never let them get ahead of you with multiple faults all throwing codes and getting too confusing. But for the same reason, some faults aren't going to respond well to Internet forum remote diagnostics. And I've been doing this for many years now. I hope your problem is the cheap thermostat. I just changed mine this weekend BEFORE it threw a code because I didn't like the way the data looked, and now it's perfect again after deteriorating slowly for 80K miles.
 

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dont forget-- that not fixing the thermostat--- for about a year--
can cause the car to run 'cold'... and in this scenario- the computer dumps more fuel into the engine- since it thinks its cold---
some of this gas-- can overtime end up burning in the CAT...
and a failed CAT-- is an Expensive cat...
 
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