DIY Catalyst/O2 Sensor Replacement
 

I have code 16814 - Catalyst System; Bank 2 p0430 - 002 - Efficiency Below Threshold - MIL ON

Been like this since the 2nd day I had the car (I think the dealer reset it before I tested it and then again before I drove it away). It scraped past the emissions test in the last MOT and I am looking to get it fixed as the light wont go out and stay out.

I am assuming that there is excess soot in the cat. I have been advised this is the case by a reputable indie in Burwell, Cambs and black smoke/soot coming out the exhaust when revved seems to confirm this.
I have tried Cat cleaner/additive and keeping revs at around 5-6k on the motorway for a few miles but this hasnt cleared out the soot in the catalyst and the emission lamp remains on.

If this is indeed a cat replacement, has anyone attempted it themselves? I was quoted £2000 by another indie in Portsmouth which I simply cannot afford at the moment. If I knew it is a DIY case I would happily go for it on my own.

Any experience or similar tales would be greatly appreciated! As would any mechanical help in the Hampshire/Surrey region ;)

If you've got VAGcom I think you can manually activate an active DPF regeneration cycle which you should try first +++

Sorry, should have mentioned the car is a 4.2 petrol. Not sure a DPF regen would work...unless you can run the cycle on the petrol as well?

Out of curiosity, what does that involve? The idea of being able to do stuff on your car via a computer is still a novelty!:o

No DPF on a petrol.;)

Sorry I should have read your signature and worked that out! Yes only applies to diesels
DPF regen basically involves the computer repeatedly cycling the engine at quite high revs to simulate taking the car for a good thrash lol. Rather like the MOT emissions test you do need to make sure that all of your belts etc are in good order as there is always a small risk of one snapping whilst the engine is at such high strain.

IIRC The cat below efficiency error starts cropping up when the cat is 94% efficient and triggers the engine light. Even with the light on and the fault code the car should breeze through the MOT. Check the air filter to make sure its not clogged up.

Will do, thanks. It is an ex-london car so probably needs a good de-smog anyway +++

I had the same fault on my 4.2 LWB and the W12 once and it is exactly that when it drops to below 94% efficiency it triggers the emissions light to come on. Very annoying when you think to drop 6% efficient is enough to trigger the light..

My solution was acctually cataclean ... then I discovered its no more than body shop paint cellulose thinners put in a bottle and sold at 8 pounds odd..

So I ended up buying a gallon of thinners from a body shop ..

I put 1L of thinners into a quater of a tank of fuel

And went for a good blast for about 1 hour lots of 2k cruising and then 5k manual gear from 40mph to 60 70 .. so its under load ..

Do this untill you have literally 10 miles left on the dis

Then go and fill up with half a tank or so ..

Then vag com it clear fault codes and it didnt come back again..

The thinners clears all the build up of laquers in the cats

After so many stops and starts maybe 10 from memory the cel light will go out with out vag com .. but if you have it just use it.

Saves a lot of money and can be repeated before mot for emissions ect ... I actually used red x injector cleaner after doing this just to make sure the rubbers are all lubed up and not dry..

Ive done this on 3 of my A8s now that had the same fault and it worked every time apart from once when I had to repeat and do it twice .. depends how caked up the cats are I guess

Glad to hear Im not alone, I will give this a go before getting my hands properly dirty. Will post the results when done +++

No problem let us know how you get on +++

This is where I first seen it

Watch "Fixing Bad Catalytic Converters With Inefficien…" on YouTube
Fixing Bad Catalytic Converters With Inefficien…: http://youtu.be/5icTmYItwiE


Its laquer thinners he used a gallon for 150 miles ...
I used 1 liter at a time until it was sorted but if you do a long drive it would clean better I guess