The ECM stores the timing chain conditions as the learning value when the timing chain is installed. The ECM stores the amount of elongation of the timing chain in the EEPROM as the current learning value, compared with the learning value. The ECM judges that the visual check of the elongation of the timing chain is neces¬sary when the current learning value exceeds the specified value. Thus, use the scan tool MB991958 to always carry out the maintenance of the learning value related to the timing chain that is stored by the ECM after the following service.
