O2 Sensor bad again in just 2 months

[Explorer Junky]

I hope some one can help me with this one. I have a 97 Ex with 5.0 and AWD. The stupid thing has 4 O2's. I replace the passenger side rear sensor just 2 months ago. CEL came on again last night. Code was for same O2 that I just replaced. It has 193,000+ on it.checked to make sure it was tight, and wires were not frayed. Connection was tight also. Could it be that the CAT in front of it could be going bad? Please help! Come to think of it, there was a problem that the factory knew of that they didn't let out to general public with drivers side front CAT's. They would go bad before 80,000. If they did they would replace them for free, if not it was 580 outta my pocket. It went bad at 81,340!! So, my point being, drivers side front CAT has 81,000 less miles on it! Could this be it? Is it that the front right one now needs replacing?

 

[jah81592]

What is the code, generally if there is a O2 going bad quickly or cats clogging then there is a reason. Excessive EGT's, antifreeze being introduced into the exhaust stream, excessive oil burning, etc.-j

 

[Explorer Junky]

It just says number 2 sensor on pass side. Although I am smelling antifreeze when engine is hot. I think I have a leak between the intake and valve cover according to my mechanic. I have had 2 water pumps go bad in last 5 years. But I am not burning any coolant. I have not had to add any. But, I do have 193,000 on it and have original EGR valve on it! Could that be why?