Xantia Bosh Motronic MP5.1.1 Fault codes

[DspecialAE]

Hi , I too suspect a open circuit coolant temp sensor. Hard to start the 97 Xantia CT but once running all is OK. Have located sensor, but finding it impossible to disconnect the green one to test weather open circuit or not. Must be getting old! I can see it with a mirror but too many obstacles. Can remove blue plug but green one defies me. I thought a DS was difficult!!! Any hints would be appreciated.

[CitroJim]

Yes, it is bloody difficult on the CT Whoever put them there needs a good talking to!

Removing the ignition coil may help a bit, along with the ally turbo pipe...

[dangerousbrian]

does anybody know what are good reading for the green Temp Sensor(ECU Mixure Control) on the thermostat housing,i get 3500 K ohms when engine is cold, 330 ohms engine red hot! also noticed if you disconnect the brown Sensor Connector(Bitron) Even with the engine is switch off but still warm, the fan will come on, ok when cold, so beware of this! the reading for the bItron are 1712 K ohms cold to 2735 K ohms when hot( look's good to me)

[CitroJim]

The sensors sound good Brian. What you see for the green one is about right and the Bitron sensor is doing right too. It's resistance curve is right too. They are opposite as one is an NTC (negative Temperature Coefficient) and the other is a PTC (Positive temperature Coefficient) thermistor but I can't remember which is which technically.

It's normal for the fans to come on when the Bitron is disconnected; this is fail-safe behaviour to guarantee cooling if the sensor goes open-circuit.

[dangerousbrian]

I have ordered one the sensors (the green one), as i think it may be on the blink now & then, or it's a connection issue, sometimes when staring up, the engine managment like ficks on for a second & this effects the CO reading's, there all over the show, i will do a test on the new one to see if the resistance ranges are the same as my original, not sure what it could be, got a new Labdna Sensor, so that's ruled out, think i will have to drain out the Coolant & remove air filter box to change it as the green one is right low down, is it a 19mm socket, anybody any good tips in changing the sensor?

[CitroJim]

anybody any good tips in changing the sensor?

After removing the turbo pipes at their joints nearby and removing the coil and LHM reservoir you should be able to get at them.

Not sure of the size, will check later...

[CitroJim]

The size is 19mm...

[dangerousbrian]

no turbo pipes it's a 1.8 petrol mark1 Dimension, i've just about got a 19mm deep socket over the sensor & breaker bar onto it without removing anything as of yet, but will wait until the part arrives, think i'm best removing the air filter box & drain out all the coolant, not to sure if it's wise to unsrew it with coolant in as it's above the clutch where there's a grill that i think must be a vent for this, just waying things up,if it was the top blue sensor for the temp gauge it would be so much easier to do.

[CitroJim]

Sorry Brian, I had it in my head you had a Turbo CT....

[dangerousbrian]

Thats ok citrojim, I like my mark1 as i think(hope), there will beless to be going wrong.... no ABS, no A/C, no transponder, just keypad etc...

[dangerousbrian]

I got the sensor, but it has a differant connector layout & will not fit??? it's a 20K9 Engine Temp Sensor.
The original Engine temp Sensor fitted to the car which is the original one & is the Green with the yellow collar with a green plug connector which connects to it & is located on the thermostat housing bottom one with 2 other sensors above it the Brown: Bitron Sensor( controls cooling fans) & the blue one (for the temp gauge).
My green with yellow collar sensor fitted has the connector layout the same as the connector layout as on ebay item 370491865858(which is a green connector one), the one sent has that outside raised bit on the opposite side to what I need ebay item 400282302405, so it will not mate up with my green connector, there was no seal with the new one supplied(not sure if I should have one) all I can see is that the sensor it’s self has the numbers E490 1-3709 stamped on it with a green connector colour any advise would be much helpfull, do i need the seal.

[dangerousbrian]

my connector is like this

[dangerousbrian]

my Car sensor shown & look in the mirror to show inside of it

[dangerousbrian]

It's a complete mystery why the keyway will not mate up, ordered from my vin number & connector sent is a 1920K9, which is what it should be, but it does not match the plug keyway, anybody ever had keyway plug issues?

[dangerousbrian]

I have been told it could be a long superceeded part number 96131470 as mine is the original one from when the car was new & they would just change the connector if they had to fit the newer spec. and as long as the Resistance is set to the temperature required it was not a problem. if you look on ebay Item number: 370390487285 this is a 1920k9 old original & has the right connector, the newer 1920k9 seem to have a differant Keyway on them now.