Test requirements:

• No navigation-CD is inserted
• Navigation switched on
• Tire circumference adapted. See TIRE CIRCUMFERENCE, ADAPTING  .
• Impulse number/wheel rotation (GALA) adapted. See IMPULSE NUMBER/WHEEL ROTATION (GALA), CHECKING 
• Erase DTC memory. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, ERASING (FUNCTION 05)  .
• Move vehicle at a speed of at least 10 km/h
• With vehicle standing still select reverse gear for at least 2 seconds

If the production diagnostic function was performed correctly (all test requirements met) and if the navigation system is OK, the value 255 appears in Read Measuring Value Block 007 (function status register).