Problem VW Polo P0420

[Matronix]

It's fairly simple, if your second lambda after cat is switching between 0.1 and 0.9 like standard (not wide band) first lambda's in front of cat do... your cat has died, just replace and it's a problem solved. Ofcourse you can do tests with heat gun (front cat is colder then end of cat due to the process inside on a good working one) but it's quite pointless.

change is that with your yearly mot test it will fail on emissions (just slightly too high numbers most likely)

[JJacob]

Hi you should change catalyst or make a fake signal from the second oxygen sensor

[wimbuitenhuis]

Hi all,

It has been a while, but my problem is solved.
I replaced the Cat for a brand new one and the MIL stays off.
Thank you for all of your replies!

Over and out!

[ronw38]

If you get the chance re do the road test and spot the difference Cheers Ron W