Your dishwasher can become a blocked dishwasher quite easily due to food amongst other foreign objects that wash down the Drain Hole, if this problem arises the best way to deal with it is by:
No.1. Check under the kitchen sink to make sure the kitchen sink trap is clear where the blocked dishwasher Drains, if all is free under the kitchen sink proceed to
No.2. Trace the waste pipe from the kitchen sink to the outside Drain and make sure the Drain outside isn’t blocked, if all is free on the Drain which the blocked dishwasher waste goes into then proceed to step
No.3. You have now determined the blockage is between the blocked dishwasher and the kitchen sink trap, try to unblock inside dishwasher, if all fails do not hesitate to call your SOS Bradford Drainage.