[V8] Code 2341 - disconnected OXS, still rough, plus exhaust hissing

urq urq at pacbell.net
Tue Feb 3 20:27:46 PST 2009

If so, why didn't things pick up when the OXS is disconnected?  The OXS or
FPR may indeed be (or have been) bad, but if so, the exhaust hissing
indicates that the extra rich exhaust caused damage to the cats.  

I must say that I don't think it is wise to recommend connecting the ground
for the 4-wire OXS to anything other than the engine block.  If things get
better at all after grounding to the car body you must have had a really bad
OXS.  By connecting the ground of the OXS to the body of the car you are
guaranteeing that the ECU will get a signal which is affected by
battery/alternator load.  People seem to think that there's such a bad
connection between the crossover pipe and the engine block that a good
connection to the shiny ground on the body of the car *has* got to be better
... but since the OXS current is very small the resistance is less of an

If you look at the wiring diagram for the PT/ABH and focus on how the ground
wires are arranged between the ECU and the engine, the grounding was
designed specifically to provide a reference for the sending units which is
not affected by the current induced voltage changes on the circuits for the
output devices (injectors, ignition coils, solenoids).  By connecting the
OXS ground as you have the reference for the OXS signal is having to pass
through the high current ground braid that goes from the body of the car to
the engine block.  

There are at least two bolts on the back of the engine which were intended
for providing a proper reference.  It is perfectly acceptable to recommend
someone use a 4-wire OXS, but for anyone who chooses to do so, look for
these points on the engine and figure out a way to connect the OXS ground
wire to one of these points.  

Steve B
San Jose, CA (USA)

-----Original Message-----

I'm gonna go with you just got a bad O2 Sensor, and when you replace it 
You should use a 4wire unit, Run the extra ground that you have on the 
4wire one up to the drivers strut tower and ground it with the rad fan. 

More information about the V8 mailing list