I get a p420 code on my Dodge Ram 1500. I changed the cats and it was clear for about a month. Now the check engine light turned on again with the same 420 code. Could it be something else?

P0420 DODGE - Catalyst System Efficiency Bank 1 - Possible causes - Three way catalyst converter Bank 1 - Exhaust tube - Intake air leaks - Fuel injectors may be faulty - Fuel injector leaks - Spark plugs may be faulty - Improper ignition timing - Engine Control Module (ECM)... As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first. The code is detected when - Three way catalytic converter Bank 1 does not operate properly. - Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.