Citroen Xsara - Citroen xsara ? ECU fault

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Mon 10 May 2010 19:21
Citroen Xsara - Citroen xsara ? ECU fault - xsara

Hi I have a Citroen xsara 1.4i LX Y Reg.Taken in due to leak (possibly coolant) and warning lights and alarm coming on due to engine temp.Garage replaced the head gasket (skimmed and pressure tested) new radiator.Also had new clutch and section of exhaust in order to pass MOT.Had car back two days and exactly same engine over heat problem same warning lights. Garage took it back thought it was a sensor problem so they 'tracked' electrics to see if they had broken anything.They could not find a problem so sent it for electical testing.Not sure what happend then other than they got a 'download' from Citroen. Got the car back (not really sure what had been diagnosed or fixed possibly new sensor put in) I do know that they put in a new water pump. Now car is coughing and jumping when it has been driven for over 30mins. they checked ECU for codes (there were about six of them) they cleared these off and i took the car back the next day and there were about six codes again. Two of them matched original codes one related to coolant temp the other causing the ECU to put to much petrol in the fuel mix which is the reason for the car 'coughing' they are convinced that the ECU is faulty because they have replaced the coolant temp sensor already. Is this correct? I get the feeling I am being fobbed off because they do not really know what is wrong so they just want to replace the whole ECU as an easy option. Ta Clare

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Wed 13 Jun 2012 15:42
Citroen Xsara - Citroen xsara ? ECU fault - Jubeloo

So long after the original message was posted. I thought this may be helpful to anyone that has the same problem. To cut a long story short, I had the exact same problem. It seems that there is a common fault with XSARA ECU's. They can make the engine only fire on 3 cylinders. Or as in Clares case, the head gasket went and pre it going most likely was only firing on 3 cylinders. The head gasket got milled and refitted. BUT, for some reason it seems to bring out this common fault. So even when the head gasket is fixed, the ECU thinks 3 cylinders and not four. So yes a replacement ECU is needed. The confusion within the ECU causes what is known as 'spikes'....the spikes prevent the ECY from functioning...

This is only my experience and understanding. I bought a used 'but working ECU from ebay, same serial numbers and so on.....but, went to be recoded and the recoding bods say that they need to have the exsisting code for the replacement one in order to put a new code in to code it to my car.

I had my Xsara since new and lover her to bits...so if I can even put a suggestion forward to help out my garage, then that would be great.

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Wed 13 Jun 2012 15:52
Citroen Xsara - Citroen xsara ? ECU fault - injection doc

Most common problem is coil pack, now when these spike it damages the ECU.

Alway fit a new coil pack with an ECU. I would be inclined to check the wiring, especially where it loops down rear of engine and make sure there are no air leaks around the inlet manifold.

The ECU will also shut a cylinder down if its misfiring to save damage to the cat.

Sounds more like it needs someone who knows what they are doing!

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