If you checked the drain pump reservoir and the problem still persists, you may have a pump with a damaged motor/impeller, or something lodged in one of the drain lines. In particular, the drain line that runs from the bottom of the wash tub to the inlet side of the pump.

I recommend you remove the inlet hose, first and inspect for clogs. In is common for small garments to become lodged in this area and restrict water flow to the drain pump. Check the output drain line for obstructions as well.

It does not take much to damage this small drain pumps. The error code is generated if the drain cycle exceeds 8 minutes. So...if the impeller or motor become damaged, and the pump does not pull water at the correct volume, you may still experience the drain error. In this case, you will have to replace the pump in order to get the error to clear. The following link explains how:

http://www.fixya.com/support/r3574350-replacing_the_drain_pump_in_a_front_load

Replacements can be purchased at any of the following websites:

searspartrsdirect.com
pcappliancerepair.com
appliancepartspros.com
repairclinic.com

Prices vary between sites, so shop and compare. the first three sites listed also have helpful exploded view parts illustrations to assist you with locating and properly identifying the parts you may need.

If you have any questions, please post back and let me know. I hope this helps you.