VDO M4 WR Notice D'utilisation Abrégée page 62

Recalibrating the altitude
Why is it necessary to recalibrate the M4?
The M4 measures the current air pressure and
converts it into an altitude measurement.
The air pressure changes daily depending on
the weather. This leads to a constantly changing
current altitude measurement.
HOWEVER: your home start altitude has not
changed. During recalibration, the currently
measured air pressure is recalculated on the
basis of a reference value – the preset start
altitude for your home. Following recalibration,
the M4 again correctly displays the home start
altitude as the current altitude.
To now calibrate the cycle computer, press and
hold the ALTI button until the menu opens.
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