s1 xantia central locking help

[aerodynamica]

Hi all, would anyone know the cause of the problem: close and lock door, by remote or by key and all doors lock but then immediately unlock. Any further attempt results in the same until it overheats and goes inop for a while.
I think it's something to do with the driver's lock barrel, solenoid or both but just not sure.
Anyone have a past fix for this? It does cure itself for a few days but soon returns. I'm having to pull out the fuse on occasion and close all manually but that leaves the fuel filler unlocked.

[VertVega]

In my S2 Xantia same behavior of the central locking system was caused by
the stuck/dirty/sticky front door lock. Some cleaning and lubrication helped.

Most probably one the front doors is causing this problem. Try to see which
one is slower to react or noisy. You can sit in the car and make this test.
Central locking must get "locked signal" from doors almost at the same time.
If one of them is slow to react then it unlocks immediately. This doesn't include
rear doors.

Another option is the broken wire but then you'll see clearly that the lock doesn't react at all.
As far as I understood this is not your case.

[xantia_v6]

Try locking the doors using the key (or maybe the inside buttons). If it stays locked when locked from one door, then that is probably the faulty lock.

[aerodynamica]

Thanks guys, yes it does it if you use the key AND if you use the remote. The key is a bit worn it seems as it sometimes doesn't turn the barrel and needs a slight wriggle or pressure while turning.

I did wonder for a while if the interior button was actually the cause as it seemed to be fitted badly by the previous owner and the behaviour seemed worse after I refitted this. I sprayed aerosol GT-85 in and around the interior button and the barrel and latch and so far it's working well so here's hoping!