Two people (including children) should never attempt to use a single seat belt. This could increase the severity of injuries in case of an accident.
Kia Cee'd JD Service Manual: Front Seat Belt Buckle Components and components location
Component Location
1. Front seat belt buckle
...
Kia Cee'd JD Service Manual: Spark Plug Repair procedures
Inspection
[On vehicle inspection]
1.
Accelerate the engine to about 3,000 rpm 3 times or more.
2.
Remove the spark plug.
3.
Check the spark plug visually.
If the electrode is dry, th ...