He needs a new sensor regardless. If the campaign has not been done, mr "T" will pick up the tab. It it has, Trp gets to treat. The campaign replaces both sensors. I would replace both regardless of who is paying the bill. The sensors can be purchased individually or in a "kit" containing both.
Loose: 89465-69115 and 89465-69125, list $120.50 EACH.
Kit: 89465-60110, list $220.03 for both.
As you can see it's a bit cheaper to get the kit.
My oxygen sensor code on my Toyota Previa keep popping up every month or so, I would just reset the computer. This was my second Previa and wondered why it didn't have the power that the other one did?? After a year, the CE light stayed on and I replaced the oxygen sensor. WOW it was like adding a super charger to it! I then sold it.
On one of those car shows, they said that you should change the oxygen sensor as you would the spark plugs but didn't say how often. He was talking about the Camry at that time. He said that oxygen sensors start to go bad before they send a bad signal to computer.
So if your power is not what it use to be, maybe its the oxygen sensor. We 94 people had ours changed for free, at least the frist time. I don't know how long they should last on the 80??