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Club XM Forum > Petrol Specific Issues
Auto diagnosis lamp do?
I've solved the problems I was having with the indicators on my newly acquired 93 2.0i Prestige....but this lamp keeps coming on.
Must get a manual! biggrin.gif
Cheers, HB
It's the engine management light. If it lights it indicates some kind of issue, perhaps a dodgy sensor reading or similar. If it's coming on persistently it may be time to read the fault codes from the ECU.
Could it just be the Lamba Sensor is knackered?
Thanks chaps.....I guess what I meant was what does the engine diagnosis...erm diagnose.
PS Are Peter Russek manuals any good? Never heard of them before!
Cheers, HB

Russek has published separate manuals for petrol and diesel XMs. I have found them good on engine and suspension.


Hi HB, and everyone else,

Russak book is ok.. I have one for the covereage of the V6 12 and 24v engines, but could well be much better, as it does NOT use photos for illustration, just VERY poor diagrams/ lined pictures

As xmexec says, good for engine and fuel, but no so good for anything else, least of all electrical diagrams! Only for the Injection systems...

Buy cheap if you can, under a tenner if possible..

Thanks......left work this morning and the XM was flashing its indicators at me.
Don't know you think its jealous of the CX in the garage biggrin.gif
Ahhh....Citroens and electics....don't yah just love them!
Cheers, HB
Hi Harry

It is like a dog wagging its tail. Your XM is so pleased that someone lavishes attention on it that it will think up all manner of little quirks to remind you of why you like it so much.
Be joyous that it is only flashing you.


Are you sure the flashing indicators are not just the alarm? My K 2.0i Presteige has been known to do this when leaving the sunroof open in wind or when driving with central locking engaged (clicker has now failed and not in use).
Looked under the bonnet today and all the airbox fasteners were loose, tightened them up. Light didn't come on ......... for a long time. Certainly a LOT less frequently than before....would the diagnosis thing flag up too much air in the mixture????
Also adjusted the throttle and kick down cable.....big difference, much smoother gear changing etc.
Still want my CX back wink.gif
Cheers, Carl
Hi Carl,

The airbox definitely would not cause the engine management light to come on. You have some other issue which is being recognised by the ecu.

Essentially an ecu is 'simply' a central brain. Its function is to receive incoming signals, perform a mathematical calculation based on the sensed values and send out the result to some actuators in the field. In the main there are up to 10 input sensors feeding information to the ecu but only 2(diesel) or 4(petrol) outputs to field actuators. In the diesel only the injection timing and the injected amount are adjusted. In the petrol you have 4 injectors (or 1 if single point injection). In some cases they both have one more for the control of the turbo wastegate function.

In all cases whether the signal is incoming or outgoing there is a remote piece of equipment at the far end of the cable. The ecu continually monitors each remote device for electrical continuity and a sensed value within the programmed range. If electrical continuity is lost or the sensor returns a value outwith its range (perhaps because of, say, dirty contacts, resulting in a higher than normal resistance) then the ecu will illuminate the engine management light on the dash and store a code in the ecu which represents the fault. It also usually gopes into 'limp home mode' which, as it suggests, permits just enough engine performance to limp to the garage. A sensor which sees a value within its range whether it be higher or lower than normal will not be recognised as a sensor or actuator failure. It will simply send an alarm to the respective warning light on the dash or if you have one, to the dot matrix display.

Since your car is a series 1 then you will be able to get the engine management light on the dash to flash in a predetermined pattern to signify the current fault. Just look in the self help section for the instructions on how to do this. All you will need is a paper clip.

Once you have determined the fault code please come back and we'll help to fix the problem.


noz cool.gif

It would be useful if you put your model and RP number in your signature for future reference. Just click on 'My Controls' at the top right of this screen, 'edit my signature' at the bottom left of the next and fill in the details in the white box in the middle of the following screen.
Thanks Noz...have opened the pdf file and will try and get a reading.To be honest, can't really understand the paper clip thing/diagram as electrics are a black art to me. Could you explain in REALLY REALLY simple terms what to do next?
PS Signature should be OK now
Further to the previous comments on the Peter Russek manual. I have one and it tells me that the XM has inboard front disc brakes - not very impressive!

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