Compression (V12)
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 2003 BMW Z8, 2003 BMW Z4, 2003 BMW X5, 2003 BMW M5, and 2003 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.
Compression on V12 engine can only be checked with a BMW-specific Diagnosis and Information System (DIS). Remove engine cover. Remove spark plug from 12th cylinder. See Fig 1. Connect DIS tester. Connect charger. Call up diagnosis on DIS tester. Follow DIS tester instructions. A mechanical compression pressure check is not possible.