Seems to be a trend. I guess when your car has over 300K miles, these things happen.

The O2 wire broke off on the ECU side of the pigtail that sits above the CAS. There's no wire left to splice the pigtail back on.

Is there anything special about the pigtail? I just clipped off the pigtail on the O2 sensor side (plenty of wire left to reattach) and temporarily attached the ECU end of the wire to the O2 sensor end.

Is that going to be an issue?

Thanks!