Exhaust and fumes entering cabin - what should I do?

I have fumes entering the cabin of my Mercedes-Benz E320. I can only shut it out by using the internal air circulation switch. The garage has said it was the cat filter blocking and I should drive it hard to clear it, but I cannot do that all the time - what do you suggest?

Asked on 5 May 2015 by GDL

Answered by Honest John
You could try a product like 'Cataclean', but if the cat matrix is broken up or hopelessly blocked, the obvious answer is to replace the catalytic converter entirely.

Also, the fact that fumes are entering the car implies that there is a leakage somewhere else in the system, possibly a cracked manifold or a joint, and these fumes will be harmful CO that could kill you, not CO2.
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