I have a Focus 1.4 cl 03 reg with 110000 miles on the clock, for the last few months I get an eggy smell coming from the heaters when moving. I have checked the battery and the cells have enough distilled water. As its a bog standard car it has no A/C. Could it be the cat going, if so how can I check? Also I have never changed the pollen filter.

If it is the cat you should sooner or later get the engine management warning light, stick your head out of the door when you park up at home and give it a little rev you would smell the cat from outside also, and the pollen filter is unlikely but you could take it out and sniff it, otherwise there is something funky in the heating vents.

I have a Focus 1.4 cl 03 reg with 110000 miles on the clock, for the last few months I get an eggy smell coming from the heaters when moving. I have checked the battery and the cells have enough distilled water. As its a bog standard car it has no A/C. Could it be the cat going, if so how can I check? Also I have never changed the pollen filter.

It is common that a pollen filter smells like egg when funges has grown on it and requires changing,

If the car wasn't a ford, id say change the filter yourself,

But ford pollen filter housings can leak if not resealed correctly and some filter changes require seal change too.

So for this id take it to the dealers atleast then if it leaks then you get a free interior vallet

Where it is very likely to be the pollen filter, just have a sniff in the windscreen washer bottle first. I spent ages trying to work out what the smell was on an old Golf I owned years ago only to find it was the windscreen wash that had gone off.