Bitron sensor

[rolyh]

Hi,
Does anybody know where the Bitron densor/cooant senser and ECU is on a Xantia V6?

Rolyh

[CitroJim]

Yes, Bitron (brown) sensor is screwed into the side of the rear bank cylinder head and is quite a lot of fun to get at. The green coolant temperature sensor that drives the Engine ECU is screwed into the top water manifold attached to the front bank cylinder head and is just a couple of inches up from the top hose connection. Very easy to get at once the airbox is removed...

The Bitron ECU (the one that controls the fans) is mounted in the same place as on all Xantias. Under the front panel below the LH headlight.

[xantia_v6]

I saw your post on the other thread... I have had the intermittent temperature light and stop warning on 2 V6s, and in both cases it was fixed by a new Bitron sensor. Curiously, in one case, the sensor had been recently changed by the dealer, for the same symptoms. I don't think the Bitron sensor contacts corrode on a V6, due to the location.

I changed the last one by just removing the airbox and the air hose from the throttle body, without draining the coolant, so it can be done without fuss!

[rolyh]

Thanks CitroJim,
My temperature gauge reads correctly, so can I assume that the green coolant sensor is OK?
Also when you refer to the Bitron ECO box being under the front left side head Lamp, is that there nearside? Sorry to sound dim but I'm never sure which way people are facing when giving the side of the car.
Which is easier to get to the Bitron ECO or the sensor?
I ask as I have read that on the net how to check the Bitron with a DVM, and if it is easier to get access to the Bitron ECO maybe I could check out the sensor by removing the sensor cable and check the Bitron sensor out. Do get to the Bitron ECO box do I need to remove the front grill etc?

Rolyh

[rolyh]

Thanks Xantia_v6,
Yes, this the second time the sensor has been changed, it was replaced by a local dealer in October; I wish I could find the bill. I have seen the air filter box and throttle cable, but I can only see screws for lifting the lid on the box to change a filter, are the screws that hold the box to the engine inside the box? Or on the outside?


Rolyh

[rolyh]

Hi,
One extra piece of information is that when I switch on the aircon I could not hear the air compressor engage. If the gas is low would that cause the problems that I'm experiencing? because the gas pressure switch did not connect. I ask because the aircon was regassed a few weeks back, and was not low in at the time.
Though with the fans on full it is hard to hear anything.
Rolyh

[xantia_v6]

Thanks Xantia_v6,
Yes, this the second time the sensor has been changed, it was replaced by a local dealer in October; I wish I could find the bill. I have seen the air filter box and throttle cable, but I can only see screws for lifting the lid on the box to change a filter, are the screws that hold the box to the engine inside the box? Or on the outside?


Rolyh

I was actually referring to my car having had the sensor changed twice, it came with the receipt, and I found the old sensor dropped beside the battery. The sensor that the dealer fitted must have been faulty, because the owner took the car back, and the dealer then replaced the coolant level sensor.

Once you have the lid off the air box, it is not screwed on, it is pressed onto rubber buffers on the battery tray and just lifts up.

Hi,
One extra piece of information is that when I switch on the aircon I could not hear the air compressor engage. If the gas is low would that cause the problems that I'm experiencing? because the gas pressure switch did not connect. I ask because the aircon was regassed a few weeks back, and was not low in at the time.
Though with the fans on full it is hard to hear anything.
Rolyh

If the aircon is switched off, it shouldn't briong on the warning light, but the warning light does disable the aircon.

BTW, the sensor is much easier to reach than the control box. My faulty sensors measured OK at room temperature.

[rolyh]

Thanks xantia_v6,
I'll go outside now and try and get access to the Bitron sensor now.

Rolyh

[Stempy]

Thanks CitroJim,
My temperature gauge reads correctly, so can I assume that the green coolant sensor is OK?
Also when you refer to the Bitron ECO box being under the front left side head Lamp, is that there nearside? Sorry to sound dim but I'm never sure which way people are facing when giving the side of the car.
Which is easier to get to the Bitron ECO or the sensor?
I ask as I have read that on the net how to check the Bitron with a DVM, and if it is easier to get access to the Bitron ECO maybe I could check out the sensor by removing the sensor cable and check the Bitron sensor out. Do get to the Bitron ECO box do I need to remove the front grill etc?

Rolyh

I think the temp gauge is controlled by a third blue sensor right at the back of the engine. The green one is just for engine management. All three sensors are subject to failures, had to change both green and brown on my now departed V6 Xantia.

[CitroJim]

I think the temp gauge is controlled by a third blue sensor right at the back of the engine. The green one is just for engine management. All three sensors are subject to failures, had to change both green and brown on my now departed V6 Xantia.

That's right. The blue sensor is screwed into the rear bank head very low down and effectively reads bottom hose temperature which is why the gauge often reads apparently very low (around 60 degrees) in normal forward motion...

LH and RH sides of the car are as you would see them if you sit in the driver's seat looking forward as if driving. I didn’t know if you were a left-hooker but for RHD then yes, LH is passenger side or nearside...

The Bitron ECU is a devil to get at but luckily very rarely fails. Good job too!

[rolyh]

Hi All,
I have the air filter box part out,( to get it fully out I would need to remove the battery to get access to a small bracket to undo a bolt).
I have exposed the throttle mechanism, but I cannot see the Bitron sensor in this area, it was getting a bit dark last night so I have taken a few photos of the area which I can attach to this thread, once I find out how to do it. I shall start a bit earlier to night to see if I can find this elusive Bitron sensor

Rolyh

[CitroJim]

There you are Roly, a picture of the offending sensor circled



The airbox will come off without removing any bracketry, just be careful of the inlet air temperature sensor..

[CitroJim]

Roly, the above was taken with the inlet manifold off but it just made it clearer for the picture - there is no need to do so to get at the sensor.

Check the connections as they do get damp from anti-freeze from the plumbers' nightmare above it...

[rolyh]

Hi Jim,
Thank you very much, that makes it all very much clearer, I shall take a look to night.

Rolyh

[rolyh]

Hi all,
I have part success, In that the problem is cured but how long for I don't know,
Thanks to everyone for there help especially Jim with drawing,, without his help I would not have found this elusive Bitron sensor.
Last night I pulled the air filter box completely off and was able to see the brown Bitron sensor attached to the engine quite a long way back under the Throttle mechanism. I tried to get the socket off and assumed it was a spring that just needed press, but even though my hands are small I could not get it off. But I followed the cable to back its next connection where it joins the wiring loom, where I thought that I would be able to check the resistance readings. But Unfortunately I could not get that one off either.
Anyway in the end I waggled (tech term) the plug within the socket of the Bitron sensor so that the contacts would rub together and hopefully improve contact, switched the ignition on, and great; no high speed fan. Put it all back together and all is fine at present, and if the problem occurs again I know the area of the problem.
The Forum is great and with the members help we would not be able to keep these cars on the road.

Rolyh