probably just need to replace a bad O2 sensor. They are about 60 bucks each for a Genuine OEM one and it's about a 15-20 minute job to replace a sensor, they are threaded into the Y pipe before and after the cat... I wouldn't be surprised if the Dealer charges you 300-400 for the work if you take it there.
This error code has been up since Wed. Tonight, Sat, after we have dinner out I go to start the truck. The truck misfires upon start-up (note: this happens every once in a while; LR tech says it has something to do with the magnet in the stem of the steering wheel) & when I re-start the truck, wouldn't you know, the service engine light soon is now gone. Turned it on/off a few times; not on. WTF?