fail mot

HI all
Well my car failed it's mot for the first time to day. It failed on the CO test and the HC test.
The CO was 0.91 the first time and 0.51 the second time and the HC passed the first time but failed the second time any ideas as to what needs doing as the mech was not very forth coming. Is it a new cat do you think? These were all on the fast idle, the natural idle was OK

If you have an aftermarket(cheap) cat fitted they need to be very hot to work effectively.
Judging by the reduction in the second reading it looks as if the cat was just starting to get hot enough.

Can you give the car a damn good long thrashing and ask him to do the gas test as soon as you get there?

Did you take it for an Italian tune up first :hgf: ??






Too slow :coat:

Dave its the cat which was on the car from new
No Italy tune up

I've had problems before with the exhaust gases if the cat isn't hot.
More modern cars are tending to put the cat directly after the exhaust manifold to solve this issue.

If the tickover emissions are OK, there could be an overfueling issue of course. Can you access the fault codes in OBD to check for sensor problems?

HI David
The only fault codes which I cheeked on 2 days ago were po130 and po300

PO130 is the upstream lambda sensor.
PO300 is random misfires.

Ours failed on high HC when Sue dropped it off for test. I forgot to remind her to get it nicely hot. That said, the mech, who knows our cars, tried his best.
I put some Cataclean in the tank, new air filter and applied the Thrashdee- Knackerzoffit technique prior to the test. Sailed through.

John and Sue wrote: Ours failed on high HC when Sue dropped it off for test. I forgot to remind her to get it nicely hot. That said, the mech, who knows our cars, tried his best.
I put some Cataclean in the tank, new air filter and applied the Thrashdee- Knackerzoffit technique prior to the test. Sailed through.

Mine only just got through on emissions last year so i took John's advice a couple of weeks ago and ran a can of CataClean through. The emissions this year are much lower than last.

TBH I cannot absolutely say that this is totally due to the CataClean as I've changes the throttle body to a 52mm version and put on a CDA induction kit. However, I was a bit concerned that these may have had an adverse effect, apparently not.

May be worth trying CataClean for £15 and getting the cat good and hot before the retest.

Good luck!

Robin

Cataclean is available via Eurocarparts via EBay mail order at 11.99 inc delivery.
Cheaper than t'shop.