my O2 sensor keeps going out on bank A. first I get p 130 then 171. I take my sensor out and bench test it and yeah it's dead. I have some oil in my connector that I washed out but the sensor itself is dead. the oil doesn't appear to be getting into the sensor

 

Bad news Amigo, you likely have a blown head gasket. Antifreeze usually is what kills the sensors...

 

I wonder how much it takes. I don't notice much/any coolant loss

 

Also check for possible shorts in the wiring harness. Might be getting shorted out and cooking the little ba*tards.

 

I should have added, if it is only one side that is dying it is almost a sure thing that side is leaking coolant. It is possible both sides are doing it, but I usually see them where only one is the offending side.

 

well that's it, im done!

 

Take a look at the spark plugs on the offending side... If you have an internal HG leak or a compromised block you will see the signs.

 

yeah I will install a new sensor and run it for a while, then look at the plugs. im sure they're probably dark now since it's been running rich for 10 miles or so

 

They actually don't run rich just because the sensors die - the ecm just reverts to programming where it will use a combination of MAF sensor readings and speed density programming (engine speed and manifold pressure) to determine fueling and spark timing. Unless you are at Altitude or have modified the engine it will run very close to stoich most of the time.

Still does not change your head gasket issue though....

 

well it definitely runs rich when this happens. it smells and the O2 sensor comes out sooty