Reading/Measuring Value Block (Function 08): Requirements

Engine coolant temperature 85°C minimum (185°F).
All electrical consumers switched OFF.
A/C switched OFF (press minus key in the A/C control head and display the unit over and over until all displays are gone.
Transmission selector lever in Park or Neutral position.
Check Diagnostic Trouble Code (DTC) memory. See RETRIEVING DIAGNOSTIC TROUBLE CODES . Then erase. See CLEARING CODES .