Picked up an almost new machine form someone who was having problems with it for free, yay me (once I fix this issue) ... Washer will stop every couple of cycles with a E21 error (water not pumping fast enough). Took apart and checked for obstruction in , trap, pump, ect and found none. Put back together and it still get an E21 error. Next I replaced the pump and checked for obstructions again and found none but I still get the occasional E21 every couple of loads. Every time I get the E21, if I blow down the drain tube with medium pressure and force the water still in the tube back down (and presumably overpower the rubber flapper back flow) into the pump impeller, I can then restart the machine, it will pump out all of the water super quick and complete its cycle. So, based on that, is there something in or attached to the main drain pipe between the tub and the pump that is supposed to vent air out of the pump area and prevent an air lock of the pump?

Thanks in advance

The back flow flapper is intact on the pump now and was also good on the pump I replaced. The reason I mentioned the flapper was because of what I have to do to get the washer to pump again I have to blow back down the discharge hose into the machine to force the flapper back in (overriding it) and allowing water from the discharge tube back into the pump impeller. I can hear bubbles come back up into the tub, I assume its air trapped down by the pump itself. Once I blow back down the discharge tube and turn the washer back on it pumps like crazy and drains the washer in seconds and will complete it cycle it does this every two to four loads. What I can't figure out is why air is getting trapped down there and how it is supposed to get out (is there a vent)? Appreciate your help!

All of that is good and no issues with the drain. This is the same thing the person who had it previously complained about but was not able to resolve. My drain hose is 1 1/4 tube, it is about 4 foot in length, the drain standpipe is 2 1/2 PVC about 4 1/2 foot above floor and the drain is loosely in the PVC maybe a 1/2 inch gap between the tune and the pipe. Once the air pocket is gone it drains very quickly. Definately got me scratching my head. The washer is like brand new otherwise.

I have a Frigidaire Affinity LAFW8000LW0. I have had nothing but problems with this brand new machine my boyfriend bought me. The E21 error being the most recent one. Pump is working flap is in place as in you Electrolux. I blow into tube and it drains. I think and will find out soon it is the drain pipe itself, it may be clogged or damaged in some way allowing air back into tube. I am going to add tubing to existing end to reach my slop tub and see if that works. If so I will call the plumber to fix my drain pipe.