Before jumping to any conclusion about the charging system, have it double checked at the battery with a device called a Vatt-40 (or newer model) as with that, one can test amperage, actual charging voltage under a load, etc. Any decent repair shop anywhere has a device like that.
If you measure anything near battery voltage at an O2 sensor, you weren't measuring O2 sensor output (which is less than 1 volt), you're measuring O2 pre-heater output from the ECU to the O2 pre-heater circuit. I'm also not sure that your volt guage is realiable so that's why I'd advise a better method. Although your shouldn't have 16 volts anywhere, one tests a charging system at the battery.

As for the codes: 132 is for battery voltage (too high or too low) but that can appear if the voltage went low at one time too (like a weak battery).
435,436 combined is USUALLY a vacuum hose leak (NOT both O2 sensors being bad) and those ABS codes (all for rear wheel sensors) usually indicate a bad ABS ECU (especially on '98 X70s where that's now common).