Got these codes about a year or so ago when I was on revo, replaced both front and rear sensors and it didn't come back until now. I am tuned with DM now that's the only difference.Yes, you would want to act on it and determine what is going on. Is car running normally?
Could you have gotten anti-sieze compound on new one when you installed it?
Wiring ok? Re-check connection?
Using rear 02 spacer?
Timing of any work on car associated with the original problem, I assume it was operating normally up until you got the codes?
I was wondering if maybe it was an old code ? I go the 02 sensor codes a couple days after putting the new one on. Kinda hard to see Chris now I live out in tustin nowIt is possible you fouled out the rear 02, I wonder if Chris has one you can borrow to check it out.