I have been lurking around for a while and joined a while ago and was planning on my first post being a little more positive as I have been making a probably futile attempt at saving a truck from the crusher as the last 2 owners badly neglected the truck. It's a 96 F150 w/ 4.9L inline 300 5 speed, everything is stock except the rust and spray paint. I have been chasing bugs for the past few days. I went for an inspection and failed with flying colors.
One of the problems is the CEL (Check Engine Light) it is giving code PO155 (O2 sensor bank 2 sensor 1 heater circuit failure).
I replaced the O2 sensor on the rear exhaust manifold, the second one back, as the O2 sensor voltage readout on the scanner was very low (less then .1 volts) even after the engine was hot. I also thought it was the B2S1 sensor, maybe I'm wrong?. The other 2 were bouncing around in voltage from about .3 volts to .790 volts with the engine running a constant 1500 rpms. Once I replaced the single o2 sensor, the other 2 sensors started reading out really low numbers, under .1 volts and sometimes 0 volts with a hot engine holding at a rough 1500 rpms. The new o2 sensor held steady, and steadily increased in voltage as I increased the RPMs, so I assume it is working normally.
I don't know if it's related, or just a bad coincidence but while I was trying to get voltage readouts from the scan tool the truck had a power surge and the red battery light is on and the voltage gauge is reading just off the front of "Normal". After the surge, the battery reads 11.9 volts and drops very slowly as the truck runs. I assume the alternator
the bed, or maybe just to voltage regulator.
I cleared the codes after i put in a new O2 sensor, but before I did, I had codes: PO155, PO141, PO135, P1401, P1137.
Thanks in advance for any advice, Jon