FC 45

[thergen at svn.net]

Dave,

For the three wire unit, is the O2 sensor element and the heater element
both grounded to the shell?  Is one of the heater wires (two white wires
for the senosrs I've seen) just a no-connect inside the O2 case? 

Thanks,
Tom


On Thu, 20 May 1999, David A. Cooley wrote:

> >
> > That's interesting.  I had a bad O2 on my GN last year
> > which caused me to fail the emissions check.  I replaced
> > it with a Bosch and with a little tuning, I was able to
> > get my emissions down to 6 pmm of HC. Max allowable is
> > 220 ppm.  Before the sensor change it blew something
> > like 330 ppm.
> >
> > Maybe the Bosch sensors work fine on the older C3 ECMs
> > but not the newer P4s ?
> 
> It's the 3 and 4 wire heated O2's that have the problem... The 3 lead, they
> ground the heater to the shell, but the units where the O2 sensing element
> has 2 wires coming out is the problem child.  GM expects the low side to be
> tied to the shell and bosch isolates it.
>