Just select the dispenser type then enter the error code from the dispenser. Click LOOKUP and if an error code is found it will be displayed. No more digging through a service manual to find obscure error codes. The keyboard layout will change slightly depending on if you have selected a Gilbarco, Tokheim, or Dresser-Wayne dispenser. NEW in version 4 Now has the ability to download a small update file when ever new error codes are released. about every 30 days the app will ask you if you want to check for updates. DISCLAIMER - This app IS NOT a substitute for a qualified service technician!