92 SL2 DOHC failed smog test - 15mph NOx

Discussion in 'Saturn S-series' started by Bill Mudd, Jun 19, 2004.

  1. Bill Mudd

    Bill Mudd Guest

    92 SL2 - DOHC

    The only part of the California smog test it
    failed was the 15mph NOx.

    My reading was 901ppm with 835ppm max allowed.
    The 25mph NOx was half the max allowed.

    The HC was 80ppm with 130ppm max and
    the CO was .06% with .80% max allowed.

    What are some of the things that might be causing
    a high NOx with everything else OK?

    I don't know much about this stuff.


    Bill Mudd
    Bill Mudd, Jun 19, 2004
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  2. Check the EGR valve for proper action. IIRC, it controls NOx.
    Philip Nasadowski, Jun 19, 2004
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  3. Bill Mudd

    James1549 Guest

    Check the EGR valve for proper action. IIRC, it controls NOx.

    That is my first thought also, but that should trigger the SES light.

    Also I am not sure the EGR valve operates at 15 mph.

    James1549, Jun 21, 2004
  4. Bill Mudd

    Mike Guest

    Probably not, but a leaking EGR (stuck partially open) might cause enough of
    a problem to fail the test, and not trigger the SES. Been there, done that!
    Mike, Jun 21, 2004
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