I asked this question a while back. Only one other board member (who doesn't post often and contacted me via PM) says they experienced the same problem. It will be interesting to see if anyone else speaks up this go-around. I will say I have a 2nd sample.............
On FJR#2, my low mile 04 ABS FJR, it occurred also, several thousand miles after I took possession of it. After speaking with the seller, this was the scoop- This FJR had a PCIII installed at one time as it was the test mule for the holeshot header system. When the prototype header came off, they removed the PCIII also (given to me in it's box), but they must have forgot to re-connect the O2 sensor, because when I went investigating, it was NOT connected. I re-connected it, reset the error code, and all has been well since.
When I started experiencing the problem with my original high mile non-ABS 04 FJR, I contacted Dynojet but they were unable to give me any useful information at all. They didn't have the slightest inkling why it was occurring, which makes sense since they are NOT experts on every bike's FI system, including the FJR. Also of note, it took a looooong time after install of the PCIII for me to get my first error code. Probably like 30-40,000 miles. Since the first occurrence however, they started coming much more regularly. The most recent only took about 1000 miles after reset and once again popped up during a top speed run - a common, but not absolute ingredient.
Unplugging the O2 sensor does not turn on any lights or other failures.
Perhaps on your FJR it doesn't.............