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[CBH]

I understand there is a small leak where the NS Cat joins the middle box the system is new only put on last week,
but if this was fixed the message I am getting is that this would not explain the CO reading.
As my guy said he does not work on Omegas very much and on other cars this not not fix the problem.
What I am trying to get my head round is is there a number of small steps I can take and get a pass or pay around £200 for new cats and still not win.
all comments gratefully received.
cbh

[TheBoy]

How do they get lamda reading, always puzzled me....

They look for the oxygen content in the exhaust.....the same as the Lambda sensor does.

Doh! Of course  

[Matchless]

Any history of problems with the cambelt or tensioners?

High CO content in the exhaust combined with excess O2 in the exhaust does suggest that the cats have failed to oxidise the CO which could point to contaminated or damaged cats....or they could be being overwhelmed by some other fault.

[albitz]

Mine have been overwhelmed by the fact that they bottom out on the top of my driveway,so it seems the innards of the cats are sitting in the centre boxes rattling like hell.

[chrisdb]

Mark is usually always right, but if you do need any cats I have a pair of timax ones for , only about 8 months old... I didn't like them though.

[CBH]

When over to the garage last night and checked there are no fault codes stored all was ok no codes.
The guy is going to try a few things today to see it he can get the reading down to MOT pass, if not it's going to have to be the new cats.
Thanks for all the advice I will post what happens next
cbh

[Kevin Wood]

.. but it failed on Lambda in addition to CO. Now, a new cat might resolve the CO issue but the Lambda reading is based on what the emissions tester thought was going into the cat - i.e. that the mixture control is incorrect.

The Lambda reading might be incorrect due to extra O2 being taken into your exhaust via the leak or it might be due to the mixture being incorrect (too lean in this case).

Either way, you may still have a problem with a new cat, and the new cat may go the same way if a mixture problem is not resolved.

I personally would resolve the exhaust leak and see if the Lambda improves. If not, find out why it's wrong. Once you've got it running with Lambda 1.0 and the CO is still out, then it's time to consider the cat.

Kevin

[CBH]

Hi
Fix the small leak and the Lamda value was ok, CO still wrong.
Removed the air cleaner and the CO when all over the place but after half an hour the CO was steady at 0.22.
Put the air filter back in and value went to 0.24 and remained stable.
So fix the drop link and fitted a new horn and it passed the MOT this morning.
I had to borrow the wife's Scenic today to come to work, it made me think what a brilliant car the Omega is.
Thanks for all the advice
cbh