Decomposing/rotten/eggy Smell 2014 Focus

[SMF1]

Hi Guys

Looking for any advice here. Over the past three days, I've noticed a smell coming from my 2014 Focus when the heater is on. The best way I can describe it is that something is seriously decomposing and rotting somewhere however I've had a look in the engine bay, looked at the pollen/air filter and checked all the obvious places. There's no fur, hair or all the usual stuff, and I haven't hit anything on the road.

There seems to be no way to recreate the smell (how to get it to actually happen) but the smell isn't there constantly. The heater can be on for ages before you get a random seriously foul burst of the smell and it's gone again after 30 seconds or so. Seen some suggestions of the EGR stuck or maybe the CAT on it's way out but no blows in the exhaust or any holes/warning lights etc.

I'm at a loss as to what it can be but the smell is so bad when it does occur that it can't be ignored.

Any ideas?

[MONDEO TXS 2.2]

Petrol or Diesel ?

Catalytic converters can smell of rotten eggs ( sulphur ) so can a DPF that's regenerating

[SMF1]

Petrol or Diesel ?

Catalytic converters can smell of rotten eggs ( sulphur ) so can a DPF that's regenerating

Sorry, it's the 1.6 Diesel (115). You can tell when it's doing a regen because the fan at the front spins and it has a distinctive noise, and it continues long after the car has stopped running, but it does it roughly one every two months or so but at the times I've smelt this, it hasn't been doing a regen.

[MONDEO TXS 2.2]

There's nothing else that should be causing that distinctive smell that I know of, rotten eggy smell is very different to decomposing flesh

[MONDEO TXS 2.2]

Just a thought . . . . the battery overcharging could emit this type of smell if it's leaking vapour

[SMF1]

There's nothing else that should be causing that distinctive smell that I know of, rotten eggy smell is very different to decomposing flesh

The first twice it happened it smelt like rotten eggs however today it smelt different, but still rotten. I've never smelt sulphur before so I don't know what it's like. Would the cat really be away on a car just over a year old anyway? Any other symptoms of a buggered cat?

[MONDEO TXS 2.2]

Not sure if your car has a cat & a DPF . . . next time you start the car let it warm up a bit & have a quick sniff around the battery - DO NOT INHALE

[SMF1]

Not sure if your car has a cat & a DPF . . . next time you start the car let it warm up a bit & have a quick sniff around the battery - DO NOT INHALE

Does have both from what I know. Will post my findings, in the meantime, all suggestions welcome.

[MONDEO TXS 2.2]

I know a wet cat stinks of rotten eggs - let us know about the battery