Panasonic NU-SC180W Operating Instructions Manual page 48

Before Requesting Service
PROBLEM
"U50" appears in the
display window.
White powder found at
steam outlet, drip tray
and oven cavity.
If it seems there is a problem with the oven, contact an authorized Service Center by Panasonic.
POSSIBLE CAUSE
The cavity temperature is
overheated.
The white powder is mineral
crystal from evaporation of
water, it is natural substance
and harmless to human body.
- Eng-47 -
(continued)
REMEDY
Operate again after cavity temperature
cooling down and "U50" disappears.
You can use auto cleaning menu with
Auto Menu 23&24 to clean the steam
system and water supply pipe to improve
condition. If crystal attached to the nozzle
or in the oven cavity, please wipe and
clean with a wring cloth. After using steam
function or cleaning, pour out the water
from the drip tray and wipe with a sponge.