I too have this code. Mine has been going off and on for months. I changed out the O2 sensor (2nd upstream is what I was told ((passenger side aka rear top))) and I still have this problem.
From my experience of this going on for the last 5-6 mos is that it hasn't hurt anything. Just wont go into Economy mode.
I put in the Bosch sensor with the part number 13958. So I went back to have them pull the code to see if a different one is out now, nope. The same code for the same sensor. I will be watching this thread to see if you get a difference diagnosis for a different sensor. I was told that the system has to reset itself and you have to go through 8-10 start cycles on it to do this. I have gone through 20+ and put over 200 miles on the van since I changed this out......and nothing has changed.
I have 2 mos till i have to do the emissions test again and need to get this fixed.
I hope you have better luck getting this fixed than I have, lol.
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EDIT: May I ask how many miles you have on yours? I have a 2007 EXL RES with just now 54k on it. When all this happened to make the light go on in the first place, I had roughly 48k on it, give or take some. Which seemed awfully early to have an O2 sensor go out.
