Opel ASTRA K 2015 Owner's Manual page 233

Low beam (1) outer bulb.
High beam (2) inner bulb.
Low beam (1)
1. Rotate the cap anticlockwise and
remove it.
2. Disengage spring clip from
retainer by pulling. Withdraw the
bulb holder from the reflector
housing.
Vehicle care
3. Detach the bulb from the bulb
holder and replace the bulb.
4. Insert the bulb holder, engaging
the two lugs into the reflector
housing and rotate clockwise to
secure.
5. Push spring clip back in place.
6. Fit the cap and rotate clockwise.
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