Fiat 500L Owner's Handbook Manual page 118

IMPORTANT When the weather is cold
or damp or after heavy rain or washing,
the surface of headlights or rear lights,
may steam up and/or form drops of
condensation on the inside. This is
a natural phenomenon due to the
difference in temperature and humidity
between the inside and the outside
of the glass which does not indicate a
fault and does not compromise the
normal operation of lighting devices.
The mist disappears quickly when the
lights are turned on, starting from
the centre of the diffuser, extending
progressively towards the edges.
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