Injectors not firing...

[J-440]

Got a Mopar 440 with a FAST XFI setup. It's all wired correctly except for (I think) the O2 sensor. Yeah, you just screw it in I know, but I cut a couple of wires that the FAST tech guy said I could. But for some reason, I get error code 16 which is a wideband fault code. I've checked fuel flow, injector wiring harness, and the injectors themselves and they are all good to go. Why would the ECU not allow the injectors to fire because of a wideband fault? Ya'lls help is always appreciated.