MOT Failure Advice

[andyman5002]

Hi guys looking for a bit of help really. Just put my saxo 1.0l through the MOT and its failed on a few things, the main thing being emissions and CV joint. Im just trying to figure out whats causing the emissions failure, heres the results:

Fast Idle Test: FAIL
CO 0.641 FAIL
HC 187 PASS
Lambda 1.030 FAIL

Second Fast Idle Test: FAIL
CO 0.720 FAIL
HC 157 PASS
Lambda 1.021 PASS

Natural Idle PASS

I was thinking it was the lambda sensor but now ive read that it could be the CAT as well. Is there anyway I can test the lambda or should I fix everything else and put some redex in and give it a good thrashing before the MOT?? :wacko:

Cheers Andy

[evans1089]

change lamba sensor.. only cure.. :y:

[shaunyboy]

So many people tink on the emissons sheet lambda means the lambda sensor when it doesnt, or it wouldent say it on the pre 1992 test. Lambda means air/fuel which indicates a problem with that area. Sometimes could be an air leak causing that. It can be the cat but that would normally throw the CO readings way off aswell, whats the airfilter like is it an open one?

Try a service aswell if it hasnt had once recently, you can try redex in the fuel system.

[rudeboiross]

My sax failed the other day on emissions on the same as yours! Tester thought it was the CAT but only got a new one fit a few months before from Kwik fit. Took it back there and got a new one fit on guarntee and got them too do a emissions test and it passed! They reckon it was a faulty CAT. Bashed it down the motorway abit before its 2nd test and this time it passsed emiisions with flying colours!

[andyman5002]

So many people tink on the emissons sheet lambda means the lambda sensor when it doesnt, or it wouldent say it on the pre 1992 test. Lambda means air/fuel which indicates a problem with that area. Sometimes could be an air leak causing that. It can be the cat but that would normally throw the CO readings way off aswell, whats the airfilter like is it an open one?

Try a service aswell if it hasnt had once recently, you can try redex in the fuel system.

I did have a K&N on it but took it off about a month ago and put it back to stock. The back box might be blowing a bit as there is some carbon on the joint. You mention the CO readings being off, it failed on that too or are they not that bad?

change lamba sensor.. only cure..
I think im going to go for one, I did change it not so long ago from a scrappy, maybe it was duff.

My sax failed the other day on emissions on the same as yours! Tester thought it was the CAT but only got a new one fit a few months before from Kwik fit. Took it back there and got a new one fit on guarntee and got them too do a emissions test and it passed! They reckon it was a faulty CAT. Bashed it down the motorway abit before its 2nd test and this time it passsed emiisions with flying colours!

I hope its not the CAT, how much did you pay for yours? Im going to take it on the motorway next time, last time it was cold when I took it in.

Cheers for the help

[LeeM]

mine had similar readings because there was a crack in the join on my front silencer. welded that up and the readings were well legal

[potatopete]

I had a new cat fitted last month, was £139 iirc.

[shaunyboy]

the co readings arent that bad mate, 0.70 and it should be 0.30 and below so its not that much out, when your in the 1.00 and above you have problems, try a service mate, if there was a hole or the exhaust was blowing it should have failed on that. What milage has it done? you can take the lambdas out and clean them 1st as they get full or carbon deposits.

[shaunyboy]

Also the hydrocarbons are bit high even though they passed which indicates to me a good service. New plugs, oil & filter and new airfilter, if you feel neccasery put some redex oneshot in and run it round then take it for a re-test, also K&N filters can throw readings off.

[shaun7086]

Also the hydrocarbons are bit high even though they passed which indicates to me a good service. New plugs, oil & filter and new airfilter, if you feel neccasery put some redex oneshot in and run it round then take it for a re-test, also K&N filters can throw readings off.

As shaunyboy says:y:

[andyman5002]

Cheers guys for the advice, ive just cleaned up the lambda and took some readings. Its switching from 0.2v - 0.8v which sounds about right so I think its ok. Ill give it a good service, I know one of the HT leads is a bit dodgy and we'll see how it goes from there.

Andy

[rudeboiross]

yehh bout £140 for new CAT!

[andyman5002]

Ive done a full service now:

Oil
Oil Filter
Air Filter
Plugs
HT Leads
Fuel Filter
Injector Cleaner


I hope it passes, got it booked in for tomorrow, ill let you know how i get on. I'm going to double check the timing tomorrow as well just to make sure.

Andy

[andyman5002]

Well i took it in and it failed again so I decided to buy a new CAT £100 inc fitting. We checked the emissions at the exhaust place and its still a fail(CO and Lambda). Dont know what to do now, i think im going to book it in a garage.

Andy

[Johnjtsmith]

I am having the same problems, still working on it, let me know if you get it passed.

[saxovtsmad]

my cat was £40 brand new after market one

[MattySmith]

im having the same kinda problems with mine on high CO its sitting well above 4.0 :(