MOT fail - lambda emissions 2005 STI
 

Hi all.

Just after a bit of advice please. My 2005 STI (PPP but with no mods) failed it’s MOT today due to the lambda reading being .1 over the maximum tolerance on second idle test.

It’s very much a weekend car and due to the crappy weather I haven’t had it out the garage for a few weeks. The MOT station is only 10 mins away of stop start driving and the tester put the high reading down to that.

Planning to go for a 30 min drive prior to
re-test in the morning to make sure it’s fully up to temp, but wondered if there was anything else I should be aware of or consider?

I only use premium unleaded but the half tank that’s in it atm has probably been in there for a month or so. Worth filling her up before testing again in case it was iffy fuel?

The good news was that there were no other advisories!

Thanks in advance.

I have had a similar issue a few times during the MOT and have been told numerous times that I don't drive it hard enough so the carbon deposits are not burning off the CAT. A couple of times with 2 different testers, one being a main dealer, they have had to take the car outside and sit on the throttle to get the CAT red hot before testing it again and it passing.

I have also used the below before a test and it seemed to work, but who really knows to be honest.

https://www.halfords.com/motoring/engine-oils-and-fluids/fuel-and-oil-additives/cataclean-500ml-616247.html?istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istFeedId=367c5610-f937-4c81-8609-f84582324cd6&istItemId=wwwxtwrx&istBid=t&_$ja=tsid :|cid:14297415498|agid:124576971583|tid:pla-330377479577|crid:539302034289|nw:u|rnd:1181610935 0461428530|dvc:c|adp:|mt:|loc:9045381&gclid=EAIaIQ obChMI4-OgqYv88wIVtJFmAh2i_wSdEAQYASABEgKFKPD_BwE
I would take the car out and make sure it is smoking hot, it will be painful to do as you will need to run it in high revs for a while to get the CAT hot enough, but it should do the trick. On the day of the test, if there are issues, you can ask the tester if he can take the car outside and get it red hot and do the second idle again. If he is friendly he may do that.

Thank you very much. I did as you advised and gave it a good run for 30 mins before the re test and it sailed through. Think it’s a sign I need to drive the car more :)

I have this problem, but I have a 100 cell sports cat, guessing not the best when car comes out of garage for mot and only does a few miles.

The tester just revs it at 3k revs, but then it hunts after abit as doesn't like it.

So I have to take it for a hard drive. I'm either going too change to a 200 cell cat, or try some cat cleaner before hand.

An Italian tune up before the MOT stopped my issues an a low use car.

Glad it worked mate, good excuse for a good blast at least once a year!

Italian? Is that a typo?

No a saying as such.

What does it mean?

Dog the life out of it.

Ah ok, get it!

Italian tune up