2003 Chevy Trailblazer rough idle

  • 6 CYL
  • 4WD
  • 13,000 MILES
I have a 2003 Chevy Trailblazer that has started ideling rough over the last couple of weeks. The car runs fine down the road and my wife says on some warmer days it seems to idle fine, just not on cooler days. I had a friend check the code and it came back with a "128", which has something to do with coolant temp if I was told right? There is also another code of "1345", or (P1345), which said something about cam / crank issue, possibly the variable cam timing sensor?

I changed a temeperature switch yesterday, not the sender for the guage / light, but another one which is located behind the altenator on the left side becasue we were told that was the problem more than likely. After completing that task I started the vehicle and it seemed to run fine, but a few minutes later we took it around the block and it started idleing rough again. This morning my wife left for work in it and it sounded fine again and she said it was running fine later in the morning. If it begins to idle rough again do you have any suggestions?

I was told by another online mechanic that the 128 code was going to be the thermostat sticking, is this a possiblity? I have not noticed the guage getting higher (hotter) than normal. Would the thermostat sticking have anything to do with a rough idle.

It acts like an older carb engine with a choke and the choke not working correctly.

Thanks and any and all help is greatly appreciated.

Do you
have the same problem?
Wednesday, December 30th, 2009 AT 10:29 AM

1 Reply

Hi You replaced the ECT which sends engine temp to PCM. The P0128 is thermostat not closing for engine to reach op. Temp. That would cause rough idle. The P01345 does cause concern but first replace thermo. And clear codes see what happens.
Thanks for donate
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Wednesday, December 30th, 2009 AT 12:05 PM

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