Error 99 is appearing on screen each time I attempt to take picture. Suggests turning off then on. Done that no joy.
Suggested sensor clean.Done that, still no joy. Reformat card. Done that...guess what, yep, still no joy...any help appreciated
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Sarah C-Cross, August 2009

My Son's 400D comes up with the same fault, in his case it seems to be caused by the flash, switching flash off seems to cure the fault, trouble is when you are in a situation when you need the flash, switching off the flash enables use of his camera but does not cure the fault

Les Pattenden, March 2011

Had this problem with my 400D. For me, turning off the automatic sensor cleaning has solved it!

Adrian Hendy, January 2011

error 99 if i remember is a coms fault code for the lens...
Have you bought a new lens?
Check the contacts?
Have you tried a different lens?
Have you gone on the canon website for a camera firmware update?

philtobinphotography, February 2010

Try a fully recharged Battery, A different CF card, Format old in a card reader if new card works. Error 99 is communication fault. Goggle for canon forums and search for error 099
If it happened after removing refitting CF card, remove CF card look into socket where card goes you are looking for bent pins or 2 pins going into the same hole in card. If bent REMOVE Both Batteries, if you try and straighten them pin may break. Look on ebay for canon eos cf repair service. But the shorting of the pins might have caused other damage.
Canon will charge £200+ I am told. Check out www.teleplancamerarepair.com $99 but you need a friend in the USA to pay for it and post it back to you. Mine is on the way to them. it cost me £16 to post it to them.

Keith Davis, August 2009