Scale can build up on a dishwasher heating element over time. In order for the dishwasher to function properly, this needs to be periodically cleaned. This is easily done.
Using lemon juice to clean the dishwasher heating element is the ideal way to remove the scale. In most instances, the scale will come off quite easily, but where the dishwasher heating element hasn’t been cleaned in a long time it might take several passes. Don’t use other types of cleaner on the heating element.
By removing both the rack in the dishwasher it should be easy to access the heating element. With most makes this is easy to do, but where there are problems, consult the owner’s manual. Don’t simply pull the racks out-remove them completely from the dishwasher.
Use a toothbrush to scrub the dishwasher cleaning element. Keep the toothbrush well moistened. Once the element is fully clean, use a damp sponge to wipe the element then leave to dry before using the dishwasher. Don’t use anything harsher than a toothbrush for scrubbing the element. It’s better to take more time and make two or more passes; to use anything more could risk damaging the heating element.