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  1. #1

    Default emissions problems....

    I have a 93' C1500 and when i took it to get the state inspection it failed the emissions test. The guy told me that the NOX level was too high. I asked him what that meant and he said he didn't know, he wasn't a mechanic. I was wondering if anyone has had this problem or maybe knows where's the right place to look first?

  2. #2


    maybe you need a new cat??
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  3. #3
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    High Deserts of SoCal


    Read my earlier posting at GMTC re: smog test fail. My problem was a high CO level, and a new cat took care of the problem. You're facing a high NOX issue which points either to the EGR, O2 sensor or cat. No way to narrow it down on your own. You'll probably have to swap out the parts in some order. How many miles on the 93? If it's over 100k, and the cat hasn't been swapped you might start there. It is a pain, because most test only places charge for a retest. Usually yoiu come out way ahead by not going to one of the test and repair places. Keep us posted.
    There is no way to happiness....happiness is the way.:yipi:  _vXMYypuKMJFw671uF2ZPhjez_j-atRmcjM2zQKpQi1JSsB75/burb1.JPG
    High Desert SoCal
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  4. #4


    The 89 Suburban I had (same engine as yours) had the same problem last year. I replaced the EGR and it actually got a little worse. I replaced the cat and it passed with flying colors. The places around here give you one free retest with in (I think) 15 days.

    99 K 1500 Suburban
    78 Silverado Big 10 w/factory 454
    00 S-10 Blazer
    1976 Trans Am
    1980 Honda CB900 Custom

  5. #5


    yea,the truck has 279k on it. I was thinking it was cat and my stepdad was thinking it was the O2 sensor. I think i'ma try the O2 sensor first for the next year because i already have a sticker for this year.

  6. #6
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    High Deserts of SoCal


    That's my motto.....why do something today that can be put off till tomorrow!

  7. #7


    HAHAHA, yeah i'm a really bad procrastinator

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