a few months ago i used to get these 2 codes
P0422 Main Catalyst Efficiency Below Threshold (Bank 1)
P0432 Main Catalyst Efficiency Below Threshold (Bank 2)

i changed the o2 sensors on those banks and now i get these 2 codes no longer do i get the first 2 codes
P0140 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
P0160 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)

and my ctaylic converter is making weird noises are those codes normal

First off, How many miles on your car? Federal emmissions warranty is 8 years or 80K miles.

Secondly, No those codes are not normal. Did you use MB OEM O2 sensors. If so, then I would check for loose connectors at the ECU.

car is an 02 with 36,000 on it its wierd how those codes came up and then after i changed the o2 senors with oem mb sensors those codes came up. were is the ecu located? do u think it might be bad o2 sensors?

thanks so much

I would confirm with a dealer that it is under warranty and then take it to them.

If you want to continue on your own then I would reinstall the old O2 sensors and see if your back to original problem.

if you say your cats are making noises they are probably bad and caused your intial codes. if you are unsure then it would be a safe bet to get it diagnosed properly before you start throwing more money into something that may not fix the problem.