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Discussion Starter · #1 ·
I've been having a CEL come on and off for a few months with no noticeable drivability issues. Problem is, NYS inspection is here and I need this fixed.

The CEL is from a P1128 too lean code. I've cleaned the MAF (it looked fine, no real dirt but I sprayed it down real good anyways), and the shop smoked the engine to detect any vacuum line leaks and got nothing. I think the O2 sensor is ruled out as well.

The shop is claiming the CEL P1128 is caused by an exhaust leak in my flex bend (which I think does have a leak). Is that even a possibility???

Anyone can point to anything else that I should look at?
 

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Discussion Starter · #3 ·
Thanks 2002GLXV6. I actually already went through that with my Vag-Com and did a 2nd gear run. I did get significantly less (about 95 g/s) than expected after cleaning the MAF but is there any indication that it is definitely bad? I mean, I just cleaned it and it looked fine. And I think it was replaced a few years back as well. There is a caveat though- I ran it on an on-ramp on 495 on the LIE and I wasn't quite able to completely floor the throttle and had to ease off well before hitting 50mph. Typical NYC traffic so that "may" factor in me getting a lower g/s than I would have liked to see. There are very little stretches of open road here for me to do a quick 2nd gear full throttle run...

I'm GIAC chipped so I think I should expect 120-130 g/s. My question is- do you think the flex joint leak would cause the g/s to be significantly less? I'm just hesitant on having the shop start replacing random stuff that they think may be causing the trim CEL.
 

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I just don't get how the leaking flex joint that (if I'm correct) is after the O2 sensor and the CAT could be the cause. The front O2 is what gives the ECU the info. But, I'm sure some of the smarter guys will be along with more help later this evening.
 

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Discussion Starter · #5 ·
Yea, that's why I'm a bit skeptical at what the shop is pointing to as the cause because I just need to pass the inspection. I can find the real issue at a later date without blindly throwing money away at problems that aren't going to fix what needs to be done now...
 

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A leak after the front O2 sensor shouldn't affect mixture in my opinion, but lower than normal fuel pressure could.
 

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Funny enough, I am not sure how to do it with the VCDS. You can use VCDS in generic mode (OBD 2), you will have there buttons for "fault codes" and "freeze frame".
 
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