Catalytic Convertor stinks - but not always..

[Patrick Daines]

So my cat really started to smell sometimes, the typical rotten egg smell etc. Very noticeable at idle when your not moving. But it only does this occasionally? Doesn't matter about engine temperature and its seems very sporadic. Also its just passed the MOT as the emissions were perfect? I Have no EML's etc and the car runs fine. Just the cat on its way out or could it be something else?

 

[R3k1355]

Checked for ECU fault codes and stuff??

Could have a dodgy sensor somewhere throwing the mixture off at random times.

 

[Bankrupt_drunk]

I think it's more likely to be a dodgy injector than the cat.