Okk so a family member has passed on an 04 Sebring LX to me. When the car is in any ignition position other than run there is no CEL. Plugin Launchtech X431 and it will get no codes. Start the car and the CEL comes on. Using launchtech X431 I am able to see P0432, but I cannot clear the code, probably because it does not seem to be storing it.

So now I am debating if I should be replacing Catalytic or if there is possibly an ECU issue because it is not storing the code

 

I'm now also noticing a knock in engine. Mostly up top. Both fuel trims are -12 and scan tool says ignition timing is 11+ btdc.

 

What motor is under the hood, Check for even a small exhaust leak, particularly around the area before the O2 downstream sensor(flex coupling in the exhaust pipe). IF motor has a EGR valve ..check for pinhole leaks in it's piping.

 

The dreaded 2.7L.... so I'm assuming the knocking sound I'm hearing is either a stuck valve or timing chain slap. And inturn this could result in coolant hitting O2s which would almost instantly kill them.