Exhaust rattle after cat fitting

[Nicol@]

Had my car MOT'ed yesterday and had the cat put on and left on.

Driving away I could hear a rattle.
Taking it back to the garage, I was told it was probably the honeycombe in the cat disintegrating.

Once the mechanic looked, he said he has adjusted the heatsheild. The car ws then quiet.

Driving the car to work today, it is rattling again. Worrying at high speed. Revs don't seem to make a difference.

Could the cat fall to pieces when it has only done just over 20k?

[BIG DUNC]

It could be possible.

If the noise was initialy curred by adjusting the heat shield, then it subsequently returned, I would get them too look at the heatshield again, in case it has moved for some reason.

[Pupp]

Been through any puddles or standing water? Have a car with a cat heat shield that gets battered by spray until it contacts the cat and/or car body, making a right racket...

[Nicol@]

No to the water and it is going back to the garage.

Thanks for the suggestions.