CO output high = failed :( ideas required

  1. Infrequent Poster Joined: May 2011 Cambridge, dartford, glasgow Posts: 212 98 MK1 VTR
    #1
    Hi there had the saxo in for an MOT yesterday and it done not too bad, scrap that actually it done blooody excellent considering its covered 111K

    It failed on the drivers seat being insecure, only down to a weld snapping while being checked. LOL

    and the CO emissions were .510 (ish) on fast idle, it passed natural idle but fairly close with 0.300 being recorded.

    If anyone can pinpoint why it it putting out too much would be amazing but thats not going to happen other than someone's best guess so here are mine:

    1. Cats old
    2. Too rich a fuel mix
    3. Blocked breather/pipe

    Could it be something else that i have forgotten about? Im pretty sure its not the lambda sensor as all other readings were good.

    The annoying thing is i can't just replace the failed part cos it could be anything of the above. Although i have bought a new cat and will hope for the best.

    Cheers
  2. Frequent Poster Joined: Mar 2011 Norwich Posts: 538 Saxos (sold), Civic
    #2
    A friend of mine got his Corsa through its MOT on emissions by replacing the spark plugs, and giving the engine a long run with some Redex in too. Not sure how far off it was to start with though
  3. Saxperience Post Whore Joined: Jan 2009 warrington Posts: 7551 posi blue mk2 2003 vtr
    #3
    mine did the same failed over and over by tiny amount on emmissions but mines a sports cat, turned out i have a tiny blow on the down pipe to centre section, once new gasket was fixed passed with flying colours.
    check for blows would be first on my list
  4. Infrequent Poster Joined: May 2011 Cambridge, dartford, glasgow Posts: 212 98 MK1 VTR
    #4
    @Tc24 cheers can't really use the redex now as the cars legally off the road and i dont fancy getting nabbed.

    @marcusd cheers but if it was sucking in air i doubt that would affect the co2 reading.
  5. Infrequent Poster Joined: Jun 2011 Gloucester Posts: 119 1.6 VTS MK1 1997 L3
    #5
    Could still be lambda. Or one of the temp sensors reading low.
  6. Infrequent Poster Joined: Feb 2012 New Ross Posts: 202 Saxo VTS/Xantia HDI
    #6
    CO is usually the cat, especially if all other readings are ok.... had a problem with mine a while ago having high CO, changed every sensor, cat, lambda, ecu the lot and no difference, in the end it was the plugs, the lad gave me the wrong iridium plugs in the factors he gave me BKR8 instead of BKR6, i put it an old standard set to try and was perfect