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Username Post: 2006 Silverado P0172, P0175        (Topic#360273)
Posts: 29

Reg: 01-04-10
03-25-20 10:31 AM - Post#2789447    

I was getting these two codes (rich bank 1, rich bank 2) consistently along with fumbly cold startups, it would run fine aside from that although long trims were both about -19 or so.

After cleaning MAF (noting interesting found) and a new air filter (rusty airbox screws needed drilled, all 4 replaced with stainless screws for $5 instead of $8 apiece for the GM part) and a new set of plugs & wires no change.

After some reading I found that the flex-fuel engines are prone to false high alcohol in fuel readings causing the PCM to run a richer F/A ratio.

I stopped by the dealership to ask about getting it straightened out and was told it'd be a minimum of $260 to scan the vehicle and flash it if that was indeed the problem.

I then talked to my local independent shop who specialized in electrics and he was not only familiar with this problem but scanned the vehicle (PCM alcohol percentage showing 53%) and reset the alcohol reading to 3% and fuel trims all normal.

$20 for this. Cold start today ran great and no MIL.

Senior Moderator
Posts: 29102
Age: 49
Loc: Texas
Reg: 08-01-03
03-25-20 12:29 PM - Post#2789452    
    In response to 400sbplow

Good info. Did the shop explain how the PCM parameters got there and how long the reset would last? It would seem if it got there before, it will get there again at some point, and a permanent fix could be investigated. $20 to a trusted shop ain't bad, though! I just doubt most people have access to shops that wouldn't charge at least an hour's labor.


06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

Posts: 29

Reg: 01-04-10
03-25-20 01:29 PM - Post#2789456    
    In response to someotherguy

Not sure. I've never run any E85 in it.

I left it for a couple of months over the winter and found a totally flat battery. I changed the battery and had the MIL on when I ran it for the first time.

The MIL came & went a couple of times but it came to a head when I needed an inspection recently so I had to act on it.

I've also looked into the battery drain (since two months shouldn't be a problem and hasn't in the past) and understand that the instrument cluster is usually the culprit but that's a different subject.

Edited by 400sbplow on 03-25-20 01:34 PM. Reason for edit: No reason given.

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