O2 sensor fakeouts

[Roger Heflin]

On Sat, 15 May 1999, Frederic Breitwieser wrote:

> Greetings,
> 
> I haven't been keeping up with many of these threads, but I noticed that
> the O2 fakeout diagrams I've seen posted here still had the O2 sensor...
> are the purpose of the diagrams to "adjust" the output of the O2 sensor
> on a live vehicle?  Or, are they for testing an ECM on a bench?  Because
> if its the latter, you don't need the sensor obviously, and a 5 or 10
> turn 100K pot and a D battery would do the trick nicely.
> 
> D cell + ---->  --\
>                   /    100k 5 or 10 turn pot
>                   \
>                   / <------- to o2 sensor wire on ECM
>                   \
>                   /
> D cell - --0--> --\
>            |
>            |
>          ground
> 
> 
> 
> Or, have I once again missed the point?
> 
I believe the O2 fake sensors are used on ODBII vehicles that have two
pairs of O2 sensors.  The circuit may be the circuit to make the one
after the CAT look right when the CAT is missing or bad.

			Roger