V2 Reading Code Incorrectly

RitzBlitz

Member
May 20, 2010
113
0
16
Ritzville, Wa
Member on another forum had a problem with their Autocal reading P0128 as P0621. After diagnosing their charging system they had their code checked on the spot at the parts store with their scanner and realized it was P0128.

I've had P0128 pop up occasionally lately and have my old PPE in my truck as I was selling it on craigslist. Had it pop up again tonight and decided I'd read it with my V2 to see if it did the same thing. My V2 read it as P0621 as well. Checked it immediately after to rule out a coincidence (and my truck deciding to break down all over the place :eek:) and confirmed it was indeed P0128.

Both trucks are 2006s.

Anyone else have this problem? Is there a fix for this that I have neglected to find?
 

Harbin_22

Active member
Dec 4, 2010
3,858
7
38
Southern Indiana
I had a LMM yesterday that we started without the MAF hooked up, set a light, checked with V2 and it spit out an AC pressure switch code. I know it was from the MAF being unhooked. I will try to duplicate it again and send it in.
 

coker6303

Keep Calm and Chive On!!
Aug 6, 2009
2,484
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40
Houston, TX
I had a LMM yesterday that we started without the MAF hooked up, set a light, checked with V2 and it spit out an AC pressure switch code. I know it was from the MAF being unhooked. I will try to duplicate it again and send it in.

Hmmm... I've been tripping the "AC clutch" code off and on for a couple months. I'll check into it further now that you mentioned your hiccup. My AC works great
 

NAFLASH

New member
Aug 22, 2010
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P0621 was also popping up on a coworkers 2006 Duramax. Scanned with a techII and it came up as a P0128. Changed thermostats and everything was good.

The same issue occurs with an LMM when #8 glow plug goes bad. It will throw an AC compressor code.
 

RitzBlitz

Member
May 20, 2010
113
0
16
Ritzville, Wa
Issue has never been reported, but we'd like to investigate and need a trace file to do so.

If you didn't clear the code, can you please email me the trace file. Instructions on how to generate the trace file can be found here.

Either V8 standalone or V7 pass through.

http://support.efilive.com/kb_article.php?ref=8552-EOAJ-5912

Cheers
Cindy

Cindy,

I already cleared the code but I will wait for it to come up again before I replace my thermostats and get you the trace file.
 

Kappa9012

MAN.... I Broke it again.
Aug 5, 2008
694
0
16
Peoria Il
last winter i popped the a/c compressor switch code and found on here where others posted it as being a bad glow plug and sure enough it was a bad #8.