CEL was on reading O2 Sensor Downstream/Heater Circuit Malfuntion/ Random Cylinder Misfires

I've got the Vibrant header with high flow cat. Oxygen sensor plug/wire was too short to just plug back in, so I soldiered in a few extra inches of O2 wire, and covered it in heat shrink wrap. Put it back on the car. Drove about 2 miles and the CEL went off. All was good for about two weeks, now CEL is back on reading the same three codes.



Any ideas?

 

check 02 sensor for damage and recheck the wires you added go to the correct location

FYI if you replace a sensor ONLY use an ACDELCO sensor, the bosch ones listed for this application do not enable the o2 Heater properly

 

The O2 sensor puts out mil volt to the pcm,any change in resistance will or may cause a issue.
This could include wire length,or water in the connection.

 

Pulled it out again today, everything looks fine, no cuts in any of the wires, all the soldiered areas are still protected by the heat shrink. Doesn't make any sense to me, like I said, the CEL was on, we fixed the 02 sensor, and the light went back off. For two weeks now, everythings been smooth, Is it possible that the 02 sensors is too deep in the exhaust? Like does it need some kind of washer or something to prevent it from setting to deep and getting crazy readings with the aftermarket header and cat?

Car's also been have a pretty shitty idle here lately too, The Tach doesn't jump around, just stays right around 900rpms, but the muffler, and sound of the car is what sounds rough....don't know if the two are related, just thought id put that out there