Keep the O2 sensor ground separate and on the engine!  Connecting it's
ground to other grounds creates the possibility that voltage returning
to ground from one of the other sensors will contaminate the O2 ground.
When grounds are bundled together at a single point there is danger that
some or all will start to float together away from the true ground. When
this happens, and it very often does in automotive life, the current
flowing through one or more sensors can raise the voltage at the
floating point and thus ruin the ground reference that the more
sensitive sensors rely on. The o2 sensor needs a clean and true ground
or it will mislead the ECU into misadjusting the mixture.

Mark

Todd Last wrote:

> Does it make any sence to have the O2 sensor, ECU and any other critical sensor gounds all ground at the same point?  Or are you risking a ground loop by doing this?
>
> With the problems with the ECU and O2 sencor and grounds, I was wondering if making an alternate ground path that both are tied to would be a good idea or not?
>
> In my Van, the DPO crimped on an extra ground which is simply screwed into the sheet metal under the seat.
>
>
> Todd
> '88 Westy
>