C8 - filler cap sensor

[masterofinsanity]

Replaced the filler cap sensor on my C8 today £105 from citroen for 2 metres of wire!! lexia was showing filler cap sensor short circuit to earth and filler cap not present, well it made no difference whatsoever.
If i disconnect the filler cap harness it says filler cap present, if i connect it it says filler cap absent, have tries to trace the wiring back further and can see no broken wires or damaged sheathing.

any ideas or do i put a 2 pole switch by the filler cap and manually switch it on and off every time i fill up?

[myglaren]

Unless I am mistaken the switch is operated by a small magnet in the filler cap - has the magnet fallen off?
I have heard of this happening.

[masterofinsanity]

both magnets are still present thanks, might get another magnet just to test it.

[masterofinsanity]

the new cable I got from citroen is twice as long as the old so im thinking it must missout the connector under the car and go direct to wherever it goes, does anyone know where this sensor connects to as it runs over the top of the fuel tank by the looks