FC 45

[David A. Cooley]

> Hey guys,  I could use some advice on this.  I have a 93 s10 blazer with
> cpi.  It's setting a fualt 45.  Using the scan tool I am seeing that
> when I cruize at highway speeds the O2 sensor voltage will hold at .85
> volts and after a couple of minutes it will set the code and kick it out
> of closed loop.  It then holds O2 volts at .92 and will stay usually
> until I go back to start stop driving at which point the ecm goes back
> to closed loop and the O2 sensor starts swinging from .1 to .8 volts.
> Any ideas as to what I am not seeing here?

A couple ideas... Fuel pressure regulator could be stuck, Fuel return line
could be plugged, or the PCM could have a problem.
Was there anything that was done to the truck immediately before this
started happenning? (Replace the O2 sensor maybe with a Bosch unit???)