what is this sender?

[92EcoDiesel Jetta]

What is the one circled in blue? It's on the coolant flange on the end of the head with 4 wires. I looked in the Bently electrical section and could not find it.

[ilikevwdiesel]

it's the glow plug temp sensor. to be sure that's what it is warm up the engine, shut it off, then disconnect that sensor. turn on the ignition but don't start it. If the glow plug lite comes on for around 30 seconds then you can be certain that's what  it is.

[flapjack]

Isn't that what the temp gauge works from as well?

[rallydiesel]

On mine that sender was used for the a/c thermostat. Follow the wires. If they connect anywhere into the rad fan/thermoswitch/a/c relay mess it's the a/c thermostat. If not, it's either the glowplug duration switch or the coolant temp sensor (interchangable, I tried it last week).

[Zulfiqar]

by the looks it has 2 separate circuits on earthed and one live - the live one maybe the A/C kill and the second one looks like a sensor for the temp needle.. - what is written on the sensor 120 or 119 degrees?? = the 120 would be a temp gauge switch the 119 is a A/C compressor cutoff - I also have that in my NA

my wiring diagram shows a relay in the fusepanel connected to it, but my car didnt have any sort of wiring to connect it, I just made it work off negative to trip the A/C compressor relay I put in the engine room

[regcheeseman]

It's two temp senders in one body one for guage, one for glow circuit - which is maybe why it's not shown in the bently.

That said - the wire colours are all wrong but that probably a UK/US issue.

We don't get A/C so I could be wrong on that score too. 

[92EcoDiesel Jetta]

Thanks for the replies! I was able to follow one of the 4 wires from that sender to the AC compressor clutch, which then goes to what looks like a pressure switch (circled in pic), which then goes to the sender on the bottom of the radiator. Looks like the compressor clutch is in series with 2 temp sensors and one pressure switch to cut out the AC. The wiring diagram in the Bently for the 92 Ecodiesel unfortunately does not show any AC components. I still need to figure out what the other 2 wires in the sender is for. I know it's not for the glow plug or coolant temp gauge since those are on the coolant flange on the face of the head (bet #3&#4 glow plugs).