P0420 Catalyst System Efficiency Below Threshold

[Tony.F]

Hi,

I have a 2004 UK Spec 2.0l Petrol Rav 4 with a  "P0420 - or Catalyst System Efficiency Below Threshold" error.

Several garages have looked at this, changed both O2 sensors, new Battery - dealer suggested new cat, despite the fact that it passed the MOT emissions test with perfect results.

It runs fine, economy is 38 mpg - good for this car - seems nothing wrong with it

One garage suggested changing petrol stations.

Basically nobody can fix it, I reset the light  and it comes back on within 100 miles or so.

Internet research suggests that it is an over strict ECU check setting which declares the cat spent long before the emissions start to suffer

Does anyone know how to set the system to ignore this code and not display the light - can it be done with Techstream, or know anyone who can disable he check for this "false" error 

Thanks, Tony.