Googling the error message told me that the vent assembly needed to be replaced. Ordered a new one from these guys, watched a YouTube video on how to replace the vent assembly and was back in business in less than 30 minutes. I was lucky because I had enough slack in all of the hoses and electric wire that I could pull the dishwasher out far enough without disconnecting anything. That probably saved me an hour of time spent getting under the dishwasher, disconnecting hoses and then reconnecting.