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2003 trailblazer_lt
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84 Posts
Discussion Starter · #1 ·
Last month, while on vacation in Colorado, I kept getting P0105 and pending P0105 codes, according to my code reader. The check engine light first came on as we rolled in to Durango (Elev. ~6500'). I didn't have the cruise control set on the way in, so it may have thrown a pending code earlier. The last code was set on the way home near Dumas, TX, where the elevation is ~3600'. The rest of the trip to Louisiana was code-free.

While in Colorado for 2 weeks, a full-blown or pending P0105 (or both) would be thrown within 10-15 minutes of cranking the truck. Occasionally, after clearing the initial codes, they would be thrown again on the same trip. Twice, there was an accompanying P0172 code, but this was not as persistent as the MAP sensor code.

I had a similar problem with the check engine light coming on 3 years ago in the same area, but I didn't have a code reader at the time to know which codes were responsible. I suspect the same ones, but that's pure speculation, at this point.

Down on low ground, I have not had this problem with the P0105 code, either before or after the trip. I have since cleaned the throttle body, but I have no way of knowing if this fixes anything since it'll be a couple years before we make it back to high ground. I never had any of the common symptoms of a dirty throttle body. I will scrub it again right before we make that trip, though.

Has anybody else experienced this in high altitudes? Do the low surface pressures screw with the MAP sensor?
 

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2002 gmc envoy_slt
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31 Posts
Had the exact same thing happen to me last week while visiting CO and UT. It seemed to only happen after I had stopped the engine at the higher elevation, and then started it up again. Never have had an issue since returning home.

Out of curiousity, do you have a stock PCM? or tuned? I had mine tuned by PCMforless about 70k miles ago and this is the first time it's thrown a code.
 

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2007 chevy trailblazer_ls
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1,782 Posts
I live in Aurora, Co @5100+ feet. Daily I have no issues. If I go to Colorado Springs my Altitude changes in 75 miles or so one way.

Aurora 5471 ft
Monument 6975 ft
Co Springs 6035 - 7200
I get the code when I get to the Springs the light comes on. Once I get back home the light takes a few miles inside Denver to reset. Dealer has checked it a few times First time they replaced one injector, since that the have no Idea. I have not had any issues otherwise.
 

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2003 gmc envoy_sle
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254 Posts
On a trip leaving from Whistler BC we encountered alotof slow moving traffic on the mountain highways. I can't remember the exact code that triggered the check engine light, but I lost all throttle the moment it came on.

Luckily it happened when there was enough of a shoulder to park on. The reason for no throttle? The engine stalled. Tried to turn over the engine. no response. I cleared the code and tried the engine again... It roared to life as if nothing happened? :weird:

It has only ever happened once, and it was at high elevation. I am sooo happy I bought the Scangauge before leaving for that trip.
 
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