Hi i also have the same error code (12/22) with a sony plasma PFM500-AW2E, i don't use the screen anymore because it would just power off every 5 minutes with the error codes on the side. i found the meaning of the error codes on a different forum, it is indeed related to some voltage problem... (i will try to post the URL here) If you have these codes it doesn't look good because someone said it not worth fixing it for that price (couple of thousand dollars).

I have recently purchased this same TV from a friend. I started getting the 12 22 error message and the screen goes blank. There is also an error 53 associated with this. I found someone selling one and he said that the 12 22 is related to the power control board. This TV worked fine at my friends house so I suspect there is something wrong with the electrical wiring in my house. I am having an electrician come out and check it this week.