What is the function of this sensor?

[sanlo]

Hey everyone,
I'm the recent owner of a Xsara 2001 1.6 (tu5jp4). The car had a rough life with previous owners doing sketchy repairs and weird mods.
I had a lot of electrical issues (still trying to fix most of it), so I'm trying to find obvious wrong things with it. A few weeks ago I went under the car and found this sensor disconnected. The sensor (2 plugs) is located right under the oil filter.
I believe that it is an oil pressure sensor, but i cant be sure. Also, i have no idea where is the wire that its supposed to connect it. I found a lone loose wire, but it doesn't fit on it.

I would appreciate any help you guys can give.
Thank you.

[white exec]

Any chance of a photo, and what colour is the connector, and wires connecting to it?
Just one two-way connector?
Do post your VIN, which will help identify.

[xantia_v6]

Sometimes these engines have an oil temperature sensor that is only used on high-spec cars, and there is no matching wiring on lower-spec cars.

[sanlo]

Here is a couple of photos that i took. Those photos were taken from the underside of the car.
The VIN is VF7**************[VIN obfuscated, can be read by forum staff]

I don't know if its easy to see, but the plug connector is a yellow two-way connector and the loose single wire is red with a nylon sleeve.

[picassodad]

I find that parts exploded views can be really helpfull in identifying stuff......is the oil filter below the unit?? and does the oil pressure light work on the dash.

[GiveMeABreak]

This is a Xsara II Petrol 1.6i 16V TU5JP4 with manual 5 speed.

The oil pressure switch is item 20.

Here is the location in detail of the sensors:
As you can see both the water temperature sensor and the oil temp. sensor are in close proximity and would seem to share the same warning trigger wire (405).

This is the Injection Circuit:

Sensors
4025: engine oil temperature sensor + thermal switch
1220: engine coolant temperature sensor

Wiring
405: Coolant temperature warning command
1366A: engine coolant temperature signal
1357: engine coolant temperature earth /

[xantia_v6]

I think that there is an error in the information above, and 4025 is actually a coolant sensor. The diagram above does not show it with the correct yellow connector, and the symbol shows water rather than oil. It would also seem unusual to locate an oil temperature sensor so far from a body of oil.

If the car was not originally intended to use a sensor that is fitted to the standard engine, the sensor may not show up in the wiring diagrams for that car.

[GiveMeABreak]

I think I know what has happened. The diagrams are correct, but as with these earlier models there is limited electronic documentation. What is missing is the warning circuits which include the oil warning. So what I have posted is correct - but is not the oil switch it seems, but it is the name given to the sensor.

I have compared with a C3 with the same engine and this does have the missing diagrams:

C3 Engine same as the diagram I posted previously for the Xsara, showing the same sensors:

and here again for the C3 that does have the additional diagrams, it shows the oil pressure warning switch specifically at 4110, and 4120 is the Engine Oil level Sensor.

I did think it a little odd to be sharing a warning signal with a different sensor - but sometimes I wonder why I am surprised with these vehicles

[sanlo]

Thank you everybody for the detailed reply. I will try to look for the missing wire using those diagrams.
I will try to post the result tomorrow. Thanks!

[sanlo]

Hey there. It really was the Oil pressure switch. Also, I was mistaken on the color, it was actually brown.
I guess some mechanic yanked the connector and broke it, leaving the yellow part inside. After cleaning it up and buying a new connector, the oil warning light lits up when the engine is stopped and light off the I start the engine.



I also found another loose connector (blue). Anyone have any idea whats used for?
I wanted to comment that the car isn't showing any engine problems and error codes, its just that the sketchiness of previous repairs left me a bit worried about it.



Thanks!

[GiveMeABreak]

I can't be sure what the yellow one is - or the others from a picture - you would need to look at a wire on the insulation and provide a code number.

There are various coloured connectors, so this is a guess:
4 pin Blue could be the front downstream oxygen sensor
3 pin white could be the vehicle speed sensor
4 pin grey could be the ignition coil or inlet air pressure sensor
4 pin green could be the front upstream oxygen sensor

But these are just colours for some connectors that I can see and may not be these at all.