Just for fun, I decided to go out and "test" my oxygen sensor today, by
which I mean I warmed up the car, and then checked the voltage coming off
the sensor wire with the van at idle.  I got readings of around .52 volts,
which maybe seems okay (?), but the voltage was steady, not oscillating (it
stayed between .51 and .53 volts always).  Does this mean my engine is never
entering closed loop operation?  If so, what are the standard things to
check, since the O2 sensor seems okay?

Thanks,
Wes