No voltage from ANY o2 sensors

[cornflakes]

I know this is an old thread but here I am reading it in 2019 and like so many others, the OP never updated the status. I have been trying to get a 98 SOHC to run on all 6 cylinders for a while now and replaced nearly every sensor in the truck as well as fuel injectors, EGR, PCV, plugs, plug wires, coil pack, etc. 5 different scanners and all 5 read the o2 sensors on my 99 OHV just fine but those same 5 scanners read 0v -100% on all o2 sensors on the 98. Every thread I read just has a bunch of possibilities but no one ever bothers to come back and say what if anything fixed their problem.

Any update on this for the OP or others whom chimed in with the same issue?

 

[2000StreetRod]

Does the PCM go into closed loop? If so, then it is reading the pre-cat O2 sensors and your scanner is not able to get and display the voltages from the PCM. Can your scanner read and display the short term fuel trims? If so, do they cycle between slightly rich and slightly lean?