Anybody with a DB9 had to have all the Cats replaced (MY08)?

[NTEL]

If so, what were the underlying reasons why they failed?

[BamfordMike]

NTEL said:

If so, what were the underlying reasons why they failed?

is not a common problem so doubt you will get many saying they have.

what's your problem?

if secondary cats, don't bother with replacement, the cat isn't needed for mot or is monitored, so either remove the cat from can or fit decat piped.

if upstream cats then you will have efficiency problem and getting p0420 or P0430 error code and emissions light is on. Main problem with replacement of primary cats / manifolds is that engine / subframe will need a drop

[NTEL]

Hi Mike, thanks for the reply. This has been an ongoing problem and to be fair to the dealer and AM they are trying to sort it. I can hear a vacuum leak when the throttle is "stabbed". Its coming from behind the engine on the drivers side. There is also a smell of rotten eggs, under heavy acceleration, suggesting overfueling. I have plugged in two different fault readers and no codes are logged but when I looked at what the lambdas are doing, two of them (one on each side) look very lazy and are not switching as I would expect.

Initially the secondary cats were changed but the smell was still present. I ended up taking them out making some decat pipes. The car is back at the dealers and they are in the process of changing the primary cats. Unfortunately they don't really seem to be looking for the underlying problem and don't really seem too keen on listening to what I have to say. I'm convinced there is an unmetered vacuum leak and the lambdas are faulty causing the car to over fuel. The drivers side exhaust is always very sooty too.