Hoping to get some input/help.

Codes that have shown up;
118401 Mixture Control AFR too lean
118002 Micture ECU: Mixture too Rich
12BD52 Lambda probe before catalytic converter, line error: interruption pump current line
128901 Lambda probe before catalytic converter, dynamic: slow reaction
1E0001 Idle speed control: Speed too high.

All codes were pulled from my JB4. Current modifications to car is JB4 and catless dp. Last night my buddy and I put a O2 bung onto my downpipe in hopes of deleting the CEL so I can get smogged. Still learning all this car stuff since I’m new to all of it. If anyone can give me some input on what to look for that’d be great! Thank you

 

You can check the codes and faults here:
https://bmwfault.codes

First thing I would do, remove the JB4. The only code you should be related to the cat missing. All the codes you have listed would make me think you have a bad primary O2 sensor. (or it got buggered during the down pipe install)

 

The lad above is right. Sounds like you either have poorly designed spacers or fouled one of the sensors wile swapping in the spacers.

Last but not least, ditch the Jb4, they are known to cause some pretty obscure/funky issues on occasion.