O2 Sensor

You have 2 O2 sensors?

Mike

Ed Wojciechowski wrote:

Your '96 is OBD II compliant, this means you can extract the codes quickly and easily with commercially available diagnostic equipment. Many auto parts stores will let you use the equipment free of charge on the assumption that the O2 Sensor(s) is(have) failed and you will come back in and buy them from the clerk on duty. The diagnostic tool will also reset the circuit and turn the Check light off.

This is the weird part about my Jeep, I can and have done just that, gone to the parts store and they hooked up the diagnostic tool and it read O2 sensor upstream blah blah blah. I also can do the key trick. I have two sensors, but if the other one at the cat went bad, wouldn't the code read downstream?

--> Your '96 is OBD II compliant, this means you can extract the codes

In theory, it should. But the key trick came about with OBD I, which turns out to be a boondoggle from the perspective of consumers. OBD II is much better for the consumer because it provides uniforimity of design, which means that consumers can figure out what's wrong with the car, fix it, and reset the computer. The key trick still works with OBD II, but why struggle with it when you can use the diagnostic tool for free -- and this clears the code for you so you can be sure you are chasing a new malfunciton, or the same one you just got done working on.

The Upstream Sensor is the one beween the motor and the CAT, the downstream sensor is after the CAT.

That's what has me baffled, I replaced the upstream and it still says it's the one that's either bad or something else is wrong. Could there be something else wrong?

--> In theory, it should. But the key trick came about with OBD I, which

I had the same thing happen. It said upstream, but after I replaced the one at the cat, the light went off and stayed off. FWIW, napa, oreilly, autozone, none of them had the correct sensor. I had to go to the stealership to get the right sensor. Dennis

I'm not sure that the code gets reset automatically when you fix the errant part, or if you have to physically reset the code yourself. I think the latter is the case though. This means you will still get the old code even with the new part. Of course, there is always the possibility that the part or the connection is somehow faulty.

Check your exhaust manifold for cracks.

Troy