Plumbers can diagnose and identify causes of dishwasher failures, relating to plumbing this may be in regards to a blocked waste pipe, poor water flow or connection or pressure issues. There are components inside a dishwasher that may require an appliance repair specialist to attend in relation to internal elements, pc boards etc.  A dishwasher may provide error codes that can indicate with the use of the owner’s manual what the issue may be. It’s  important to have a plumber attend to diagnose and identify if the issue is unknown as most commonly its a blocked outlet that will cause the dishwasher to go into error mode or potentially a restricted supply issue.