catalytic converter source besides BMW?

[67's]

I cleaned the MAF, ran a cycle of Cataclean through it, changed air filter, going to reset and take a pic of the codes if they show back up.

[Ryansbmw1]

When’s The last time the rear O2 sensor was changed? That’s usually the one responsible for showing cat inefficiency codes. Look there 1st to make sure it’s operating correctly

[67's]

Ryan, I havent ever changed it. The X5 is a 2010, and I have only had it for a year and a half, P0420 is the current code that comes up within 50 miles of resetting.

Thanks for the replys and suggestions.

Tom M

[Ryansbmw1]

If you can do some monitoring of the sensors I would. Or hell, at that age and mileage, just replace both sensors. They are due