I finally found a bad vacuum hose. I replaced it and cleared the codes. Before I was showing No Activity from all 4 O2 sensors plus a malfunction code for each sensor. Now after driving it a bit my my light came back on, but all of the No Activity codes for my 4 O2 sensors are gone. Here's are the codes I have left...

P0135
P0155
P0141
P0161

What direction would you try now to beat the last of these little grimlins back.

I'm pushing 204,000 miles now and with the help of some cyber friends we'll keep this beast going!

 

they are all O2 codes still... when was the last time you put sensors in? do you have any coolant or oil leaks?

 

Those are O2 short circuit codes, all 4 sensors are dead.

 

I replaced all 4 about 3 months ago.
I noticed a few nights ago that I have a slight leak on the hose that went to the throttle body heater plate. The heater plate gasket went bad about 3 years ago so I bypassed with the hose. There's enough coolant on there that I could see the green coolant. I also have a little oil leaking around my valve cover.

 

i would try and get warranty replacement sensors, reason i was asking about leaks as if they are being leaked on it could kill an o2.

 

So you still have either no activity codes, malfunction codes and one heater circuit malfunction.
Try and get the warranty. By the way, what brand did you buy?

 

I don't know what kind they were. I got them from Atlantic British. I'll contact them tomorrow and hopefully we can figure something out.
She's leaked a little from everywhere since 75,000 miles. I just keep an eye on the fluids and have never really had a big drop of any of them. My front two sensors have always had oil on them, but they usually last 50,000 or so.