Audi A4 Cab 1.8T 2004 - Startup stuttering start since yesterday?!?

[chris2010]

Since buying the car ive had to spend a considerable amount - service, new tyres, gearbox oil service, roof leak and since buying it, it started off with a EML light in the 2nd week.

Buying VACOM and going to two different garages showed up through diagnostic tests that I need a new CAT although still drivable at the moment.
The first garage quoted me £850 for a new cat plus their labour charge and there other garage quoted me £200 plus labour for a 2nd hand CAT.

So far since purchasing the car (2months) I have covered 2k miles.

Anyway yesterday afternoon when getting into the car, when switching the ignition on the dash lights looked a little dimmer then usual.
I then decided to start the engine where it didnt do anything at al but cut the light off.
I turned the key back so the dash lights were off and proceeded again.

This time I got the engine to try to startup but after a few cycles of attempts it died off again and left the ESP symbol light on.
I decided to take the key out and wait a min and try again.
This time upon inserting the key and and turning it so just the dash lights come on, I pressed the brake pad.
I don't know but to me it seemed much looser but it could just be me.

I then tried again and this time I got the engine to start and I pressed the ESP light which turned it off on the dash.

This has happened a few times now since yesterday afternoon and once the engine is started I am having no issues but even after a 10min drive, stop start is struggling.

Is this the battery or could this be related to the CAT?

Thanks

[Crasher]

Cat failure is very unusual, I would get a second opinion first AND I would want to know why the cat had failed, spontaneous failure just does not happen in my experience, something always causes it. If you have a new cat fitted, it is likely to be an aftermarket part and these are no where near as strong as the VAG parts and if there is an issue, the new cat will soon fail, something that will not be covered by the warranty. What was the fault code? Your starting problem sounds like a weak battery.