2005 Lincoln navigator O2 sensor problem

Asked by Mkeeney Apr 05, 2019 at 01:23 AM

Question type: Maintenance & Repair

Working on an 05 navigator, i have a Verus Pro
scan tool and when I view live data for the O2
sensors, everything starts normal, mv start to rise
for all 4 sensors.  Once they reach a few hundred
mv, after about 1 minute of engine running, bank 1
sensor 2 drops to zero mv and stays there.  The
engine begins to run rough and eventually stalls
out, also I get dark smoke from the exhaust.  I have
changed out all 4 sensors and that particular one
several times.. If I unplug it, the tool reads 13mv,
plug it back in and it will drop to zero again or stay
at 13 until I restart the car then drop to 0.  Is this
something anybody has seen before? Is it in the
harness? Is my cat plugged up?

Mkeeney answered 5 years ago

Also I am not getting a trouble code from the computer either... Sometimes I will get a fuel rail pressure sensor voltage too high code but if I clear it out it will stay gone for some time.

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Sirkut_Interrupted answered 5 years ago

When the downstream on bank is stuck low what does the upstream look like? Is it switching? If it is what millivolt is it switching at? Should be around 100 to 800 or 900 mv

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