So I got my scanguage 2 and I’m throwing a p0420 code that clears itself a couple of days after fill up. Doesn’t effect performance at all but I want to clear code via the scanguage. I have tried but get no response from the scanguage and I have swapped the troubleshooting setting in the advanced setup menu with same results. Are we not able to clear the codes?

 

You didn't mention the model you have, but here is how I do it on my 2005 R50 with my generic code reader. I turn the car on but do not start it. Next I plug in the code reader and read the codes. Finally I clear them. If the engine is running they will not clear without BMW's scanner. Hope this helps!

BTW, the P0420 code is indicating poor catalyst efficiency Either you have a bad post cat O2 sensor or a bad cat, and the code will not go away permanently until you fix the issue. If it's a bad cat and it has no impact damage, then something made it fail. This can be either an improper air/fuel ratio or the engine may be burning oil. It is extremely rare to have a catalytic converter be the primary failure.