I have an '05 1200GS with 25k miles(my first road bike, so be gentle). I have had the bike since 15k miles with no problems. However, recently on a hot day in stop and go traffic, the RED flashing light came on. I was lane splitting in stopped traffic. I quickly made it to the shoulder and turned the bike off. After checking the obvious, i.e. oil level, fuel, temp gauge, tire pressure, etc. I restarted the bike. The light went off. I continued, but repeated the process 2 more nearly random times. The warning light came on when rpm's were low and air temperature was HOT! The temperature indicator didn't show over heating.
I read online that there are issues in the blocking of the cooling coil in front of the bike. I cleaned it, though I suspected these references were more directed to 650 and 800 series. I suspected there might be a defective oil filter which I had replaced about 1000 miles before. Therefore, I replace it with another new filter and new oil even though those were rather new.
Again, today, the warning light came on in stop and go traffic when ambient temperatures were in the 90's. I quickly shut the bike off, waited a bit, re-started, and continued with no further problems. I tried to cause the light to return by lugging the engine toward lower rpm's starting from a stop to see if the low engine speed and excessive heat was to blame for reduced oil pressure (btw, I'm not absolutely certain that oil pressure is the cause of throwing the light on). I couldn't make it come on again.
For your information, I am using 20W-50 synthetic and K&N filters.
Any insight would be appreciated.