No engine temperature showing (C5 X7)

[Animal Mother]

All was well for nearly a week with the (new to me) C5 X7 Tourer 2.0Hdi (138). However, yesterday (and continued this morning) the engine coolant temp gauge isn't showing any temperature at all.

The engine oil temp is showing between 5 and 7 bars, which, depending on outside temps, appears to be about right.

The stat has been recently changed by the previous owner.

• Is it just a temp sender?
  Does the sender sit at the top end of the engine coolant system so could it be sat in air (i.e. caused by coolant loss)?
  Any other thoughts?

[GiveMeABreak]

There is no actual temperature shown in degrees.... it is just shown as segments that should remain in Zone 1.

How long is it being driven for - it can take several miles before you start to get get any bars filling in. This is the gauge and temp segments will start to fill in zone one. If it is not putting any segments up after 5 miles then something may well be wrong. However the warning in red, shown at 'A' should show up along with the STOP lamp if it ever enters zone 2

As for the outlet tank, the temp sensor is item 2 in the diagram below:

And shown in circuit below - item 10

If you still think there is a problem, and you want the part number and price, just pop your VIN here (it is automatically masked). Or if you want an owners manual and don't have one, let me know.

[Animal Mother]

Thank you Marc.
There are no cars showing on the coolant temp gauge. This is even after driving 30-50 miles. Up until yesterday it was fine and showing between 5 and 7 bars when running normally on a long run. It's not been above zone 1 while I've had the car.

I've checked the bleed screw on the thermostat housing (is that item 10?) and coolant came straight out so I believe it's unlikely the sensor/sender is sat in air only.

Are items 1, 2 and 3 (in your bottom diagram) bleeding points for coolant?

I'll check connections etc today. As the stat was recently changed the connector may have been not fitted correctly for the sensor and come loose.

If all seems ok (physically) can I do a multimeter test? Maybe put the temp sensor/sender into a cup of hot (80-90c) water and see if it sends a signal to the dash gauge?

[GiveMeABreak]

1 & 3 are the Bleed Screws, 2 is the Temp. Sensor.

It is important that the system is bled properly - do we know if it was drained and or bled properly when the last owner did it?

I can put up the bleeding procedure shortly if you want.

[Animal Mother]

1 & 3 are the Bleed Screws, 2 is the Temp. Sensor.

It is important that the system is bled properly - do we know if it was drained and or bled properly when the last owner did it?

I can put up the bleeding procedure shortly if you want.

I don't know if it was bled properly. I don't have any reason to doubt it wasn't but I can't be 100% (it was this situation, it's this car I've bought). https://www.frenchcarforum.co.uk/forum/ ... 2&start=15

The bleeding procedure would be a massive help, thank you.

[sparksie]

Good chance this is just the wire has come off the sender.
European temp senders are usually negative temp coefficient, meaning they become less resistive as temperature rises.
Accordingly, open circuit (ie disconnected) would give no gauge deflection on a normal gauge, or no bars in this case.
You can test senders, with a meter, set to measure ohms, but you need the tech spec of the sender, to make sense of your readings.
With older, analogue gauges, a simple test of the instrument and the wiring was to short the sender wire, briefly, to the block and see if the gauge went to full scale deflection. I wouldn't do this on your Citroen, though. If you can get hold of the tech spec for the sender, then you can get a resistor of a value that corresponds to mid range and substitute it for the sender, which should light up roughly half the bars, without causing upset.
If it does, you can be confident the wiring and dash are all right.

[GiveMeABreak]

The dash has a separate ECU and would throw a serious wobbly if it wasn't working and a code. It will be the temp sensor or the connection for sure. For the price, easier to replace the thing than faff about with a resistor I suspect...

[Animal Mother]

The dash has a separate ECU and would throw a serious wobbly if it wasn't working and a code. It will be the temp sensor or the connection for sure. For the price, easier to replace the thing than faff about with a resistor I suspect...

Can you share the bleeding procedure please mate?

[GiveMeABreak]

I will, just give me a while as I have to type it up manually and assemble the pics. Check back in a short while.

[Animal Mother]

I will, just give me a while as I have to type it up manually and assemble the pics. Check back in a short while.

Thanks Marc.

I've heard good things about this forum, especially related to your help. You're a champ.

[GiveMeABreak]

Oops, thanks for the reminder - your post has just reminded me to do this - will get on it now

[GiveMeABreak]

This is the official procedure for Draining, Filling & Degassing:

Tool for filling the cooling system by vacuum	Bayonet filling cylinder	Adaptor / extension for bayonet filling cylinder [0173]
Blocking Rod for Filling Cylinder	Screw-fit Filling Cylinder (without extension)	Cable Pliers for Flexible Clips

Draining the cooling system
CAUTION: The draining operation is carried out with the engine cold.

Put the vehicle on a hoist.
Remove:

• The protective panel under the engine (according to equipment)
• The de-aeration chamber plug (Carefully)

N.B.: Place a clean tray underneath the engine to recover the coolant.

Uncouple the pipe (1) (at "a"); Using tool [0165-2].

• Open the bleed screws located on the coolant outlet housing and the heater pipe.
• Allow the coolant to run out.
• Drain the cylinder block (if necessary).

CAUTION : If the tool for filling the cooling system by vacuum [01102] is used, measure the quantity of coolant drained.

Filling the cooling system

CAUTION:

• If the cooling system is contaminated, rinse with clean water.
• Always use new coolant.
• Each filling operation must always be followed by a cooling system degas operation.

Filling the cooling system by gravity
Connect the hose (1) (at "a"); Using tool [0165-2].
N.B.: Refit new clips.

"A" : Fitting with filling cylinder offset; Using the tools [0173], [0173-B], [0173-C].
"B" : Fitting with filling cylinder direct; Using tool [0173-2].

• Fit the filling cylinder, blank and adaptor assembly on the expansion chamber (according to assembly).
• Open the rod on the filling cylinder.
• Slowly fill the cooling system with clean coolant.
• Close the bleed screw when the fluid is flowing freely without any air bubbles.

N.B.: The filling cylinder should be filled to the 1 litre mark for correct bleeding of the heater matrix.

Filling using the tool for filling the cooling system by vacuum

CAUTION: Always use new coolant.
Connect the hose (1) (at "a") ; Using tool [0165-2].
N.B.: Refit new clips.

• Close the bleed screw.
• Put the equipment for filling by vacuum [01102] in place on the expansion bottle.

CAUTION: To avoid entry of air into the circuit, provide for 20 % additional coolant.
Prepare a receptacle of coolant containing the quantity of fluid drained + 20 %.
N.B.: The receptacle must be positioned slightly lower than the equipment for filling by vacuum.

• Place the cooling circuit under a vacuum to reach -0,9 bar (diagram "C"):
• Wait 10 seconds and check that the value obtained does not drop
• Fill the cooling circuit completely and wait for the return to 0 bar (diagram "D")

N.B.: The quantity of coolant filled should correspond to the quantity of fluid drained.
Repeat the operation until the cooling system is full (if necessary).
CAUTION: Remove the equipment for filling by vacuum [01102] and rinse the assembly with clean water.

Degassing and Checking the Cooling System

• Fit the charging cylinder, closer and adaptor assembly on the expansion bottle, in the case of draining using the tool for filling by vacuum [01102].
• Open the rod on the filling cylinder.
• Start the engine.

N.B.: The air conditioning control should not operate during this phase.


All Engines Except EURO 6 Emission Standard
Keep the engine speed at 1500 - 2000 rpm, up to the second cooling cycle (cooling fan(s) cutting in and out).
CAUTION: Check that there are no coolant leaks.
Stop the engine.

ESSENTIAL: Do not remove the filling cylinder while the engine is hot.

• Leave the engine to cool.
• Blank the filling cylinder using the blocking rod .
• Remove the filling cylinder , plug and adapter assembly.
• Check the coolant level when cold.
• Top up the coolant to the "max" level (Cold).

CAUTION: Do not fill the system past the max mark.

• Refit and tighten the cap on the header tank.

CAUTION: Check that the cooling system filler cap is locked (For bayonet cap).
Refit:

• The protective panel under the engine (according to equipment)
• The vehicle to its wheels

[Animal Mother]

Thank you Marc.

[sotirisk]

Hi, I can't find any information about the conversion of temperature "bars" to actual temperature.
Is there any clue of each bar range? Mine goes between 6 and 8, but I am used of stable temperature gauges.
I've found a thread describing this for the oil "gauge" but not for the coolant!

[GiveMeABreak]

Basically, there are 13 segments in the temperature display. Anything in the first 11 are within the normal operating range. Anything in 12-13 will result in a warning, the stop lamp and a message. That's just how it operates, there are no degrees shown on this display.