5.0 Passenger Side O2 Sensor Woes

[RandomNerd2000]

So here goes a new fight. A while back, I had a pesky lean code show up at random on bank 1 in my 2000 Explorer, 5.0 V8. It's got near 300K miles so I figured fuel pump. Been driving it and up until day before yesterday, the code was it. Now comes the fun, it started surging and running rough, and now I get like six or seven miles to the gallon, and upon pulling the codes, had the same lean code, pegged at full rich.

I crawled underneath, and getting to the sensor is pretty easy, outside of it's in the front of the convertor and rounded off now. I've tried heating it mildly with a blue bottle torch, and it's been soaked with PB several times the past few days and still nothing. Before I cut the wires off and make a fatal error, I've also been running MMO and Seafoam through it to hopefully clean out whatever is in there. No luck though.

Before I end up with it in the exhaust shop,anybody have a magic fix to this? I doubt I'd replace the converter in the event it messed the threads up, nor am I looking to put several hundred dollars in a truck with 300K miles that's lived hard.

 

[410Fortune]

cut the wires, use 6 point 7/8" socket see if you can get it loose
I have had to drill them out before = remove the down pipe from the truck
I have also had to cut the whole dang bung out and weld in a new one because the old threads were so fubar by the time the sensor came out, it was just easier to start fresh
95% of the time cutting the wires and using the correct 6 point socket will do it
That front sensor on the pass side is a real PITA to get to, I feel your pain

 

[RandomNerd2000]

I got tempted to just replace the downpipe if I'm honest, 300K miles and removing that cross member for the transmission? I'd about assume start over, and RA has some cheaper downpipe assemblies. New pipe, new sensors, and just drop and stick the new one back in. The trick around here is finding exhaust shops that like to do anything, I called two and the discussions with both went "with 300K miles I wouldn't put any considerable money in the convertor: