C4GP Service and Stop Light Errors

[Helena_K]

Hi, guys,
Maybe somebody had similar problem, and please keep in mind that I don't know technical terms.
I have Citroen C4 (64000 km).
Couple of weeks ago the light "Service" went on, few minutes later light "Stop!" went on, power steering stopped working, windows won't open/close, "date/time" failed.. I tried to turn off the engine and restart, sometimes it worked, sometimes not, but I was able to drive (without power-steering).
I stopped the car and in an hour I was able to restart it, but those problems appeared in a few minutes again. I took car to my mechanic, he said it is alternator, replaced it, but day later I got all those problems again. Mechanic said that the new alternator is faulty, replaced it.
Day later I had the lights "Service" and "Stop!" on, took the car to the same mechanic, he drove it for about 100 km, didn't found any problems, lights did not go on, mechanic said that it is safe to drive.
Any suggestions for technically-challenged?
Thank you in advance.

[xantia_v6]

It would be easier to guess what the problem is (or was) with some more information. Which engine model is fitted (size and petrol or diesel)?

It would also be useful to know what fault codes the mechanic read, and whether the same codes returned after the subsequent failure.

If your mechanic did not reset the fault codes, and initialise the computers properly, it is possible that the most recent warnings were a result of that, but I am just guessing.