Logic of naming actuators in VW-group is simple it contains "N" + actuator number. The actuator number is unique. Here you can find fitting location, connectors and some basic information about actuators.
To our mind, actuators information is reference, so there is only simple search by number.
The fuel shut-off
valve -N109 is only fitted in conjunction with the diesel auxiliary heater
(phased-in as from model year 2007).
JThe fuel shut-off valve -N109 shuts off the fuel line when
the auxiliary heater is switched off. When the auxiliary heater is switched on
(shortly before the metering pump -V54 is activated) the additional heater
control unit -J364 switches voltage through to the fuel shut-off valve -N109. The fuel shut-off
valve -N109 opens and allows the fuel to flow into the auxiliary heater=.
J The fuel
shut-off valve -N109, the fuel pre-heating heater element -Z66 and the glow
plug with flame monitor -Q8 can currently only be replaced together with the
burner element (the electrical wiring is sealed in a shared grommet).