Kenmore dishwasher slow drain

My Kenmore Elite model # 665-16493300 doesn’t drain properly. Every few cycles when I open door to unload, water is sitting in bottom of the washer. It doesn’t happen every cycle, every 5-10. I rinse the dishes thoroughly before I load.

What’s the problem? Thanks.

The first thing I would check is the air gap on top of the sink (if there is one). Remove the cover from the air gap and the top piece. Check it for a clog.

Remove the drain hose from the air gap (or from the garbage disposer if there is no air gap), put the end of the drain hose in a bucket, run the drain cycle and look for any foreign objects coming out.

Gene.