So I tried to get around replacing my cats by using 02 extenders. For some reason, though, I clear the codes and they keep coming back. I've used reputable O2 extenders and used them in different configurations, but the CEL keeps coming back. Are there any tricks to ensure they'll work or make them work better? I know they're effecting something because the codes keep changing from one bank to the other or back again. Any ideas? I have to get it inspected this month.

 

i did O2 simulator spliced into wires in engine bay... sorry not too sure on the extenders

 

Since the ECU wants to see a difference between the upstream and downstream sensors, you should use the extenders only on the downstream sensors.

 

I passed NYS inspection with mine, yeah they have to be put on the farthest o2 sensor ( sensors if your cali emissions like me)