My A8 is having its annual MOT on Thursday first thing in the morning.

The car has a couple of issues,

At the last MOT there was an advisory (OS Track Rod End has slight play). The car has covered 6K miles since the last MOT, and when it was suspended in the air a few weeks ago I was able to detect some movement in the joint but I have no idea how much becomes excessive and a fail. This is a cheap fix anyway, even if it does fail on this.

Whats really bugging me is the emissions test. Several times lately I have had the "Catalytic converter below efficiency - intermitent" fault on both CATS (My car has 2, one for each bank of 4 cylinders). Aparently this is triggered at 94% efficiency, so what I am hoping is that as long as the CEL stays off during the test that a 94% efficent CAT should be sufficent to pass the MOT.

Bulbs, brakes and everything else are all good from what I can tell.

The car has full time 4WD (Quattro), so I hope the testing station do as they are supposed to and do the brake test on the road otherwise who knows what damage will be done to the transfer box.

I just hope it passes, keeping fingers crossed.

Best of luck with it Manny - fingers crossed for you

I'd certainly mention it to the tester before it goes off for testing, to make sure his brain's turned on about the Quattro and that he won't be able to brake test it in the usual way!

Fingers crossed.

All MOT stations have to have a Tapley Meter or equivalent, or a plate brake tester so the awd should be ok. I'd still remind them it's 4wd though.

FWIW, are you sure the cat isn't a pre-cat ambda sensor going a bit off?

The other thing that's worth doing to help the sensors and cat IMHO are a new air filter.

Cheap to pick up and easy to fit, they can very quickly make the difference between a pass and a fail on emissions, especially so for the dervs.

The other thing that's worth doing to help the sensors and cat IMHO are a new air filter.

Cheap to pick up and easy to fit, they can very quickly make the difference between a pass and a fail on emissions, especially so for the dervs.

Dervs don't undergo an emissions test.

Good luck with the MOT. Got mine booked for a monday along with a coolant system check to try and solve my magic disappearing coolant.

do haldex 4x4's have the same issue with the brake test as the Torsen Diff's?

Dervs don't undergo an emissions test.

Good luck with the MOT. Got mine booked for a monday along with a coolant system check to try and solve my magic disappearing coolant.

Of course they do, but for dervs it's just a soot test. They rev the car to full revs, in neutral and do a series of smoke readings.

That's why they ask you about the cambelt before it goes for the test.

Either that or I've been imagining it for the last goodness knows how many years.

In terms of the petrol cars, however a clean filter also helps with these from my experience.

Edited 11 April, 201214 yr by cheezemonkhai

Of course they do, but for dervs it's just a soot test. They rev the car to full revs, in neutral and do a series of smoke readings.

That's why they ask you about the cambelt before it goes for the test.

Either that or I've been imagining it for the last goodness knows how many years.

In terms of the petrol cars, however a clean filter also helps with these from my experience.

Yes I know about that. But that's a smoke density test not emissions.

I'm sure it will be fine. If it does happen to fail on emmissions they may just want to try sticking some cat cleaner through and see if that helps.

Phil

Well its been nearly an hour since its scheduled appointment, no call yet at work.

Please phone and tell me the good / bad news.

The waiting is always the hard part.

Crossing my fingers for you. God I hate MOT time. Dreading mine on monday. Just booked it in on saturday to have the bald spare tyre replaced. I have a feeling that it might need some new CV boots (is that a fail?).

Phil

The Verdict is in.

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PASSED

Really pleased, yet to go and collect the car to see any advisories and the emissions figures, but at least I have another years certificate.

Congrats

Well done

Good news.

Car now back in my hands.

No advisories, and here are the emissions figures.

Fast Idle Test:

CO - Limit 0.20% , Reading 0.04%

HC - Limit 200ppm, Reading 13ppm

Lambda - Limit 0.97 to 1.03, Reading 1.003

Natural Idle Test:

CO - Limit 0.30% , Reading 0.01%

So no issues, and all looking good for the drive to Estepona (Costa Del Sol) in a few weeks.

Great news! Big sigh of releif!

Great sigh of relief indeed, the emissions result is far better than I expected given the cat faults that crop up regularly and no advisories either which surprised me.

All in all not bad given the cars 175,500 miles on the clock.

All sounds good. Don't think I envy your likely fuel bill for your usual Spanish trip though!

See you at castle Combe then!

Your car doesn't have a transfer box, also with the centre differential if you were to run it in the brake tester nothing would happen anyhow.