It's just a smelly cat- burning the sulphur compounds off-don't worry about it put some decent branded fuel in it - not that supermarket rubbish, it's cheap for a reason.

Yeah-I know-All fuel is the same, honest, don't start banging that drum again please.

Agreed, Focussed - don't let's start another argument about fuel, as it's VERY BORING.

It might be VERY BORING but telling the OP its the fuel is not being very constructive.

All fuel is the same from a small number of UK refineries except for a few additives added at the refinery depeandant on the brand name that may or may not be of benefit, since we don't know what they are no one can test them.

I have used supermarket fuel pretty exlusively for over 30 years now and never had an issue. When I have to revert to branded fuel, normally when we are away on holiday the car runs no better and does no more mpg.

When we had a Kia on the website there was a series of issues with cars stopping for no good reason. They were in 2 geographic areas of the country and the dealers all said the same thing, its the supermarket fuel, use only branded. The arguement fell apart when it was clear not all the cars affected had been filled with supermarket fuel and when pressed for a letter from the dealer or Kia stating that the fuel had caused the problem thus giving them evidence to make a claim from the fuel retailer the dealers and Kia refused. They knew they would loose any court case and did not wish to get involved.

As for the smell I would get the CAT examined along with checks make to the Lambda sensors etc. The smell difference is just a red herring.

Thanks so much. Popping it in for a check as I'm due to drive it to the deserlate part of West Wales with my family in will ask them to look at the cat (again) the fuel consumption is actually better since the coil replacement. I'll ask them to check the lamba as well. Sorry for stupid questions as I know jack about cars. I'm much better with motorbikes :) but having a family means I need a car as the four year old no longer fits in the top box :)

Not stupid at all, but I agree with skidpan!