O2 sensor wiring...

["Storhok, Eric (E.M.)" <estorhok@domain.elided>]

It all depends on which wires were crossed....

What is interesting is that the plugs on the 4 wire sensors are not
interchangeable.  I've changed the one on our LS as well, and noted that the
plugs are standard Bosch plugs that are unique to the heater circuit as it
is for the sensing side.

However, if he used a universal Bosch replacement, where you splice in a new
sensor things can get interesting.

Swap the 2 white wires, who cares.  One is power, the other is ground for
the heater circuit.  Swap the gray and black- it will run really odd, as the
polarity into the computer is going to be messed up.  

But, I don't think that happened, unless the mechanic is a sledge hammer
kind of guy- most mechanics are smart enough to put black on black.

The bad thing is if he crossed one of the white ones with the gray one.  One
of the 2 won't cause any harm, as its just a ground.  The one that is hot
power- that is another story.  12V into the sensor will probably damage it.
Worse than that, 12V into the computer will, too.

Ok, enough of the doom and gloom...  I'm sure that somewhere in the system
is a fuse for the heater, now that the circuits are correct, find that fuse,
and replace it, as, no doubt, it will have blow.  Then you have a heater,
and if the sensor is not broken, then you will get high voltage while the
engine is running rich.  Also, if you are running rich all the time, look
for leaks- our LS's flex coupling failed, which was a HUGE leak to the O2
sensor, computer thought it was lean, kept running more fuel to the rich
limit....  Bummer for me.

Good luck.

Eric Storhok
Powertrain System Development
Powertrain Research and Development
(313)33x75011
MD 35, FPC-B
Ford Motor Company
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