Hi pizzaguy

Thanks For the criticism, just to clarify to couple of things.
I am in the UK the label on the car door says use Ron 95 unleaded
Petrol (gas) which over here is the cheap fuel...@ £1.40 a ltr the super unleaded
Is the more expensive fuel but feel that a performance car should now and then be treated to
A high octane fuel bringing my fuel bill a month to around £500 which is a but of a kick in the nuts just for fuel lol

As far as the other car, the engine warning light came on 3 days before I put it in for mot (early) due to not wanting to drive it
Around with light on due to damaging it further.

I will try and find a code reader as kindly suggested,
But as said in start of thread, basically its more a case of oxidation biulding up on to cat converter sensor
And regularly (4-6 months) needs de oxidising to keep a true reading Of emissions...

Ha lol that's my theory anyway and it worked
Maby the title of thread is miss leading, I was trying to say try the cat cleaner for £15 before spending larger amounts on other
Solutions!

Thanks
Phil