I purchased this truck in 2006 with 100K miles for 4K$ Its a 1999 Ford F 150 4.2L for 4 years it would run good and bad thru out the years, all new O2 NTK sensors the OBDII says B2S2 PO156 live feed on B2S2 I never get a signal I think,,, and the Voltage is never over .0 to175 compared to the other 3 sensors range from 110 to 900.. I have switched all O2s around I get the same thing B2S2 low circuit.. I'n about ready the replace the PCM I see where others go out at 100K miles I have many times checked electronics/sensor without disconnecting the BATTERY.. I know!!! . finally after 285K miles I had a rebuilt motor install in April, they said it was a weak fuel pump, I'm sure its not was replaced 2 years ago by them, also OBDII everything else looks good. below are a few pics I think.. THANKS for any help or suggestions feedback I have the PATS Key system which is a pain TYPE C.. I also replaced the Cats $600 plus 150$ installed about in May 2018.