Removing spark plugs:

Fig 1: Identifying Underhood View

Courtesy of VOLVO CARS OF NORTH AMERICA.

Remove: 

• any charge air pipe over the engine.

  Seal the openings.

• the upper camshaft belt cover.
• the cover over the ignition coils.

Fig 2: Identifying Charge Air Pipe Sealed With Paper Wipe

Courtesy of VOLVO CARS OF NORTH AMERICA.

Mark up the ignition coils. 

Remove: 

• the ignition coils.

  Mark up their locations.

  Put the ignition coils to one side without disconnecting the connectors.

• the spark plugs.