Modern appliances have the ability to diagnose them selves and show you what the problem is in a form of a fault/error code.
When the code appears, make sure to write it down. This way you do not forget what the code was and reduce the chances of looking up a wrong fault code later on.
Start by looking through our library of fault codes to determine what the possible cause could be. If you can not find it on our site, Google it, but make sure the page you find will reference your brand of appliance. Many manufacturers will have similar codes but will have a different meaning, so it is important to make sure the information is relevant to the brand of your appliance.