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2004 chevy trailblazer_ls_ext
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Discussion Starter · #1 ·
Hello all,

I have some info that some of you will appreciate. I joined this site for trailblazer discussion and tried to pick some of your brains because my TB failed smog. I knew this was a crock because my TB ran perfect and emitted no visable smoke. So I thought I would ask some of you about it and even included the code that made my vehicle fail. Most of you gave me your best guess and someone actually lectured me about waiting till the last minute to fix my vehicle. I believe that there is always a way around things that are unfair and pooling knowledge can help those of us to not be dependent upon scumbags who wish to take our money and/or liberty! Knowledge is power! So I decided to go to a general automotive forum and ask the same question. Someone replied that I should disconnect the battery terminals overnight and clear the computer of the code, and drive it for about 100 miles to make sure it was cleared. I followed this advice and it worked.:laugh: So if your trailvoy suffers from occasional sensor malfunction, try this technique. Pass it on! Thanks again to all of those who really tried to help me and I look forward to speaking to you again.

nevpat
 

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2003 chevy trailblazer_ls
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5,269 Posts
What was the code that you had gotten?

I live in california- and after 147,000 miles - I just got my 1st CA smog request-
I have to get it smogged before I can renew my plates. Surprissed it took them that long to make the request.

Anyways- its one of those test where they put you on rollers while you simulate driving through all the gears.
I wonder if my CaT is still holding up...
Anyways- my plates arent due till Sept I think...
But I poured a bottle of this stuff in-- when my tank runs out- ill refuel- and head to the nearest testing center....

http://www.crcindustries.com/auto/content/prod_detail.aspx?PN=05063-6&S=N
 

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2004 chevy trailblazer_ls_ext
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Discussion Starter · #3 ·
Coolant temp code

Sorry it took so long to reply. The code at the station was P0128 Coolant temp. It was saying that the coolant temp was below the thermostat regulating temp. It was a crock because the service engine soon light still has not come back on yet. Your engine computer can snitch on you even if your car runs good. I was not about to pay a mechanic to fix a sensor or computer malfunction when my car was not polluting!
Take care,
nevpat
 

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2003 chevy trailblazer_ls
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P0128- on the trailblazer-- 90 % of the time...it basically means your thermostat is starting to fail.
If its warm where you live--- then its possible that the light comes on-- and then goes off--- because it hasnt sensed a cold engine...

If it were winter--- with nice cold temps-- believe me-- your light wont go off.

What happens is the computer expects the engine to reach a certain temp-- in a certain amount of time...
and with a working thermostat-- it always reaches that temp.
If it senses that the temp didnt reach the expected range in that time- it flags it... and after a certain # of times--- it alerts you (check engine light- P0128).

If you just happen to drive your car on a warm day--- where its warm-- and the engine reaches that temp with no problem- the light goes off...

but- your thermostat- is still flaky.

dont be surprissed if it comes back on.
at this point your thermostat has already shown that it is getting 'lazy'.
pretty soon you will have to replace it.

You may get away with driving it in hot weather- since the heat helps keep the temps up.. even with it cooling..
but come winter... if your thermostat is stuck open (failed)..
then you will be cooling your engine all the time...
the computer senses the 'cold' engine- and it runs rich all the time.
you may notice higher RPM's and longer shifts... thus higher fuel consumption and lower MPG...
also- this may lead to dumping fuel into the catalytic converter... and a cat that fails early....

I guess you can say the car is polluting- because its dumping fuel into the engine thinking its a cold engine.
 

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2005 chevy trailblazer_ls_ext
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2,671 Posts
Hello all,

I have some info that some of you will appreciate. I joined this site for trailblazer discussion and tried to pick some of your brains because my TB failed smog. I knew this was a crock because my TB ran perfect and emitted no visable smoke.
That does NOT ( I repeat - NOT) mean your TB will pass smog. It is most likely throwing a LOT of pollutants into the air. The ONLY way to tell is from a smog test.
I've had to do smog tests on vehicles since the 70's. If I had a dollar for every vehicle (including family and friend's vehicles) that ran great but still failed a smog test, I'd be a rich man!



So I thought I would ask some of you about it and even included the code that made my vehicle fail. Most of you gave me your best guess and someone actually lectured me about waiting till the last minute to fix my vehicle.
I believe that there is always a way around things that are unfair and pooling knowledge can help those of us to not be dependent upon scumbags who wish to take our money and/or liberty! Knowledge is power!
This would be funny if it wasn't so sad. How is it unfair to have smog tests? Driving a vehicle has certain responsibilities associated with it, and not grossly polluting the air is one of them.
Taking your money and/or liberty? Remember that driving is a privilege, NOT a right!

"Pooling knowledge"? If you had searched here, you might have found some people here telling you the same thing. But due to the fact MOST of us believe in fixing it right the first time, no one said that!

Your line about "someone actually lectured" you about waiting is also laughable. I reread your original post. I'd never let a check engine light remain on for that long. The engineers at GM put that light there for a reason. Roadie gave you good solid advice, and frankly you got MORE than your moneys worth!
This is one of the reasons catalytic converters die prematurely.

So I decided to go to a general automotive forum and ask the same question. Someone replied that I should disconnect the battery terminals overnight and clear the computer of the code, and drive it for about 100 miles to make sure it was cleared. I followed this advice and it worked.:laugh: So if your trailvoy suffers from occasional sensor malfunction, try this technique. Pass it on!
nevpat
First of all, this does NOT sound like a sensor failure. As was mentioned in the other post, it is most likely a thermostat getting lazy. They either stick open, and open faster than they should.
Some of us "old timers" have seen it time after time, both on this forum and our own vehicles.

Rbarrios hit the nail right on the head. You put a band aide on a cut that needed a lot of stitches. I will guarantee you that somewhere down the road your light will be back on. Not a matter of IF but a matter of when. As Rbarrios said probably when the weather gets colder.

Come back this winter and tell us we were right! We'll be looking forward to it! :D

Edit: One other thing - remember the gauges on these vehicles are KNOWN to lie. When the gauge is at 210, the actual engine temp. can be anywhere from 170 to about 230 IIRC. Many people have checked this with a scan gauge.
So just because your gauge is sitting at 210 does NOT mean it is at normal operating temperature.

Likewise, the oil pressure gauge for the I6 engine is nothing more than an idiot light. The sending unit is an on/off switch and the PCM actually controls the gauge and "guesses" at what the oil pressure "should" be.
This is not true for the V8 engines.
 

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well.. I live in Cali and my Thermostat was shot since about 9 months ago.. since it's winter now and temps have began falling, I had to swap the thermostat for a new one as I had smog coming up... I Had not had the light come for almost 3 months... it however did come on earlier this month, when outside temps were in the upper 40's ... yep coolant is lower than operating or something... I knew I needed it... so I did it and today I took the TB to get smogged... WOW... best reading I've ever gotten on any vehicle... Scanner showed no codes and emissions test would be a go... and sure enough it passed.. :)
 
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