Rear window collapsed down into the body of the door on the first day. Cause: a tiny plastic stop in the winding mechanism, worth about half a French centime, sheared the first time we tried to used the window.
As soon as the car was out of guarantee the alarm failed and no-one was able to find out why.
A month or so later the central locking system, which had always been difficult to operate with the radio command, failed completely to respond to the radio command. Again, no-one could figure out why.
The horn came loose after about a year.
Central locking system developed an interesting feature: when the passenger doors were locked, the 5th door was unlocked, and vice versa. Took several visits to the garage to fix this (the fault would be fixed, then re-occur a few days later).
Suspension bulbs have had to be changed 3 times although this car has never been off surfaced roads.
Air conditioner failed repeatedly, twice by bearings seizing, causing the clutch to slip, then by the belt slipping over the pulley, heating everthing to the point where it was ready to burst into flame. Once it failed by (according to the garage) developing a series of invisibly tiny holes in a hose allowing all the gas to escape (incidentally this was the most expensive piece of pipe I've ever heard of).
Ignition developed intermittent fault causing the engine to cut out abruptly and without warning in traffic and at speed. Took a lot of complaining to convince the garage mechanics that I wasn't hallucinating or doing it deliberately.
Accelerator cable from the pedal to the throttle snapped when accelerating (calmly) from a stop light.
Catch on the 5th door came loose and made it difficult to shut the door at all. This was fixed, but it came loose again.
On a long motorway trip the oil seal on the right front axle burst, spattering hot grease onto the exhaust, and causing the sliding joint to seize. The gradual loss of power and smoke in the wheel arch was the only external evidence to me. In the end the mechanic had to change the axle completely - an expensive oil seal!
Sudden loss of hydraulic fluid on a busy motorway (with no service stations) caused a loss of pressure for the brakes and power steering. Interesting, in the rain.
This car has been regularly serviced by Citroen agents or concessions at the prescribed intervals ever since I bought it.
On the plus side, it is a wonderfully comfortable car that holds the road admirably even in snow. It is a pleasure to drive and the space in the cab and the volume of the boot make long distance family trips more than endurable.
Unfortunately it has become a liability - we are always stressed before long trips, wondering what will go wrong this time. And of course, we can't sell the thing because nobody wants to buy an old second-hand luxury car.
I have a series of appallingly bad experiences with the Turnhout main dealer of Citroen who "serviced" my AX a number of times. Even the battery level was forgotten, as I discovered when my car would not start during the annual vehicle test (and it had had it's service 30 minutes before).
They are consequent in their approach however: they are bad and do not deviate from that line.
My car is now serviced by a Dutch main dealer which is excellent. It must be possible to find good Citroen dealers in Belgium too.
My experience with the Antwerp main dealer of Citroen was excellent in 1984 when my new BX diesel showed a serious engine fault.
The early XMs were very faulty indeed, but the specimens after '96 are MUCH better. Citroen has learned a lot about quality in the last few years (e.g. the Xantia is much more reliable than, say, an Opel Vectra - and it's also much bigger pleasure to drive).
Reports such as this one would be of much more help & value if they listed the solutions against each problem.
Easy solution - Don't BUY A CITROEN!