LG Dishwasher OE error - won't drain

[GrayRat]

Hi Appliance Gurus!

I've got an LG LDW8072ST dishwasher that has been throwing an OE error code for the last couple of weeks.  I've made sure the strainer basket in the bottom of the unit is cleaned out, and I've checked the corrugated drain hose that exits the unit, leads to the air gap under the sink, and then into the garbage disposal.  It is free from clogs.  When I try to blow air back into the dishwasher, I can hear a click, like from a check valve, and no air passes through.  But if I disconnect the whole 6 foot hose, I can blow air through it the normal direction very freely.

During the drain part of the cycle, I can hear the drain motor start and about a cup of water will come out of the hose, but then the motor stops, the water stops flowing, and I hear a high whine for a couple seconds.  Then that cycle repeats 3 or 4 times - motor starts, water starts, both stop, high whine, etc.  Then usually the OE error shows up, along with the dreaded error chime.  Yes, there is still water left in the sump.

According to the very specific yellow document I found behind the toe-kick sound insulation plate, this unit has a "Test Mode" that I can enter by holding down "Steam Cycle" and "Dual Steam" buttons, then turning on the power button.  But nothing happens when I try that.  In fact, when I hold down any of the control buttons, and try to power up the unit, nothing happens.  It doesn't power up, and no useful test mode happens.

Has anyone seen this failure before?  Anyone have any advice?

Thanks!

GrayRat

[johntech]

Part number: ABQ73503002

you need drain pump. I just did one today, same symptoms and that fixed it right up. I reccommend that you pull drain hose from sink end and hook up to a shop vac make sure that it sucks water from the tub so you can rule out a clog.

pn/  

[john63]

If the first 3 digits of the SERIAL NUMBER are within---202Kxxx to 302Kxxx

Remove the Drain Motor from the Pump Housing---and check for debris caught on the impeller (plastic/ etc)

The Drain Motor RPM is monitored/tracked by the Main Board through a Hall Sensor (on the motor)

If there's debris slowing the motor RPM---the motor will short-cycle (attempting to unjam)

Replace the original Strainer---with an improved design (Part number: ADQ73234001

)

[GrayRat]

This morning I took the drain motor out for inspection.  Before that, I ran a forced drain cycle to empty the water, and it did the same routine: motor starts, water comes out, motor stalls after 2 seconds, repeat.  But I noticed once it had finally drained all the water out, the motor ran normally - no stalls.  After removing the drain pump, I didn't find any blockage or debris in there.  But I did find that the resistance across 2 of the 3 pins (3rd one must be that Hall effect sensor, right?) was only 5 ohms or so.  Much less than the spec of 20 to 40 ohms.  I'm going to order a new motor.  Also a new strainer, as my serial number is 250Kxxx.

Thank you johntech and john63!

[GrayRat]

The new drain motor arrived last night.  It's pretty easy to remove and replace - a pro could probably do it without pulling the dishwasher out and flipping it up on its back.  The new motor didn't come with a rubber seal around it, so I swapped the one from the old motor over to it.  After 10 minutes of drain pump replacement, and 30 minutes of reinstalling, leveling, and securing the dishwasher, it drains like a champ.

Thanks again, johntech and john63!