Can anyone tell me if there’s no resistance or continuity across the wires from the N108 advance solenoid / commencement valve on the 2.5tdi fuel pump, does that mean one of the wires is broken?

There is nothing across those two wires, which is troubling.

I’m trying to determine if the N108 is duff or if the wires coming from it are maybe broken.

 

Here is a pic of the N108 valve on the bottom of the pump. The black wire is actually a sheath that covers a brown and a black wire. I need to know what readings I should get across those two wires. I’ve got nothing - no resistance and no continuity.

Any one know?

 

For future reference - if there’s no resistance or continuity across the two wires from the N108 commencement valve aka advance/timing solenoid - then it has failed.

I bought a new part BOSCH SOLENOID VALVE - 0281002265 it comes with a two pin plug that is easy to remove so the pins can be inserted into the ten pin multiplug.

Resistance across the two wires on the brand new N108 is about 15ohms which correlates to stuff I’ve read here before.

On a functioning N108 there is also continuity.

I replaced mine without removing the pump by removing the brass coloured plate at the back of the pump. It has two 5mm Allen head bolts, a t30 torx bolt and a 13mm nut. Comes off easily, then it’s two T30 torx bolts and the N108 comes off with a little diesel running out.

pics.

new & old

part numbers match:

the plate at the back of the 2.5tdi fuel pump which you need to remove:

plate removed reveals the N108 bolts

the hole for the N108 valve with the old o-ring visible at the back which needs removing - there’s a fresh one on the new Bosch part:

replace the bolts and insert the wires into the multiplug and that’s it.

hope This helps a T4 owner in future.

 

Great thread and brilliant explanation and pics !

 

Very clear thread, thank you for sharing. I have a problem which I believe may be a result of a failed N108 valve or wiring. Starts and runs fine then sporadically runs very rough, almost sounds like it knocking due to advanced timing. I'll test the resistance looking for 15 ohms and to hear the click. part is a little too expensive to just go ahead and buy a new one without checking.

 

Can’t wait to hear back……🙄🙄