Mercedes-Benz C-class Operator's Manual page 342

Insert mechanical key (4) in side opening (5) to open
latch. Press briefly (do not use mechanical key as lever)
to release battery compartment.
Remove mechanical key from side opening.
Carefully remove battery compartment in direction of
arrow (6).
Electronic main key
Instruments
Operation
and controls
5
4
6
P80.35-2025-26
Instrument
Driving
cluster display
Change batteries (7), inserting new ones under contact
spring (8) with plus (+) side facing up.
Return battery compartment into housing until locked
in place and slide mechanical key back into electronic
main key.
333
Practical hints Car care
7
8
P80.35-2027-26
Technical
Index
data