I got a P0420 code due to not having a catalytic converter between the O2 sensors...I installed the fitting with the small hole only and not the angled fitting...I will need to drive the car for a day or 2 and hopefully the P0420 code does not come back...if it does I'll install the angled extension...and if the light comes back after that then i'll just have to live with P0420...😝🤣 P.S. be sure to disconnect negative battery cable before removing sensor...