What is the function of this sensor?

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
sanlo
Posts: 19
Joined: 01 Oct 2019, 14:15
Location: Brazil
My Cars: Citroen Xsara 1.6 16v 2001
x 2

What is the function of this sensor?

Post by 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.
User avatar
white exec
Moderating Team
Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: What is the function of this sensor?

Post by 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.
Chris
User avatar
xantia_v6
Forum Admin Team
Posts: 9052
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: What is the function of this sensor?

Post by 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
Posts: 19
Joined: 01 Oct 2019, 14:15
Location: Brazil
My Cars: Citroen Xsara 1.6 16v 2001
x 2

Re: What is the function of this sensor?

Post by 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.

Image
Image
picassodad
Posts: 251
Joined: 04 Oct 2018, 14:26
Location: mid wales
My Cars: pug306, citroen picasso
x 14

Re: What is the function of this sensor?

Post by 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.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 36996
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5644

Re: What is the function of this sensor?

Post by GiveMeABreak »

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

Xsara Oil.PNG
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).
Xsara poil switch location.PNG
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 /

Image
Please Don't PM Me For Technical Help

Marc
User avatar
xantia_v6
Forum Admin Team
Posts: 9052
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: What is the function of this sensor?

Post by 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.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 36996
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5644

Re: What is the function of this sensor?

Post by 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:
C3 temp.PNG
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.
C3 oil warning.PNG
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 :o
Please Don't PM Me For Technical Help

Marc
sanlo
Posts: 19
Joined: 01 Oct 2019, 14:15
Location: Brazil
My Cars: Citroen Xsara 1.6 16v 2001
x 2

Re: What is the function of this sensor?

Post by 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
Posts: 19
Joined: 01 Oct 2019, 14:15
Location: Brazil
My Cars: Citroen Xsara 1.6 16v 2001
x 2

Re: What is the function of this sensor?

Post by 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.
Image
Image

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.

Image

Thanks!
User avatar
GiveMeABreak
Forum Admin Team
Posts: 36996
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5644

Re: What is the function of this sensor?

Post by 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.
Please Don't PM Me For Technical Help

Marc
Post Reply