A week or two after the driver's side LED taillight assembly was replaced, I started getting a message on my dashboard that said something like "REAR FOGLIGHT FAILURE". The message appeared some time between one to 30 minutes after I started the engine. But without fail, on every trip, I would get the message along with a ding-dong chime.
After looking on the Saab boards, it appears the rear fog light is just on the driver's side. This may be obvious to you Europeans, but we Americans do not use rear fog lights.
I'm taking the car in on Monday for an oil change and wanted my Saab guy to check the light issue. But I tried something simple today. I checked the owner's manual to see where the rear foglight button was, turned the light on and off, and the message has not appeared since. I think I "fixed" it!