MFC-665CW Scanner keeps saying Con...

I have a brother mfc-490cw and was having this same troubling issue. I have mine connected with the LAN. What I did to get it working again was press the MENU button. Then I went under the NETWORK item. On my machine there is a factory reset choice. I selected YES to the factory reset and then also selected YES to rebooting and when it came back up I was once again able to SCAN.

Hope this can fix your issue.

I used to be able to scan without issue, but experienced this same problem today. The printer showed as offline in my system tray even though it was not. I checked the Brother support site and saw that there was a new firmware update issued on 3/26/09, so I downloaded the update and installed it.

During the process, the printer beeped repeatedly as the firmware update was happening, and at the end of the update the system tray suddenly showed that the printer was now online. I can now scan from the Control Center, though as of right now if I try to scan by pushing the scan button on the printer itself I am still getting the "Check Connection" message.

So, it's not completely fixed but I am able to scan without issue from the Control Center interface.

Make sure you IP address in the printer settings matches the IP address with the settings in your computer. If you hit (on the actual printer)
Menu using the arrow keys go down to LAN hit OK with the arrows keys go down to WLAN (for wireless) hit OK (TCIP should be highlighted )hit OK again You will see the IP address...copy it down somewhere
THen go into your computer Control Panel Printers/faxes double click on printers and faxes find Brother printer Right click and select properties Select ports CONFIGURE your PORT name OR IP address slot should match the one you took of the printer. CLick ok...
that should work...Hope it helps someone!