Spent a happy afternoon disassembling the front passenger door on our 05-plate Fabia, after repeatedly observing the following behaviour.
If the car is unlocked with the fob, and just the front passenger door opened, it re-locks itself after a short while as if it doesn't know that door has been opened. Not 100% of the time, but more and more often.
Also; and noticed as long ago as a year back, is that sometimes when driving, the car either attempts to or actually does lock itself, partially or completely, and sometimes immediately unlocking again, often when braking or cornering. Locking and unlocking behaviours without any active input. All a bit random.
I've made previous attempts to fix this second symptom, but all unsuccessful. One involved repairing wires with cracked insulation in the drivers side a-pillar bellows, together with cleaning up and replacing some pins in the connectors at that pillar, as there was some corrosion evident, likely caused by water ingress past a poorly re-fitted rubber boot/bellows. Another was inspecting and 'contact cleaning' the same pins/connections on the passenger side. Yet another was an extremely optimistic (i.e. pointless) spraying of contact cleaner into the general area of the door-open microswitches, with no disassembly, just through the holes on the back edges of the doors.
For today's attempt, I was expecting at least the door open microswitch would need replacing, but wasn't really sure that that alone could explain both symptoms. Not done enough testing at all to be sure that what I found does cover both, but optimistic for now. Here's the lock, fully removed as per @Tech1e's guide for window regulator replacement; plus a bag containing a genuine replacement microswitch.
I didn't fancy grafting that switch into the existing wiring, following a bad experience of having to revisit this work on my Polo after trying this shortcut. Two inline crimps are supplied with these microswitches to make such a technique easy. Soldering the wires directly to the pins of the connector on the topside of the circuit board was successful back then, on that one, at the second visit. Can't really remember why I didn't completely remove the old wiring from the board, possibly reluctance to do that final bit of disassembly to get at the reverse of the board, 'twas a few years ago, I forget.
This is what the board looks like before complete removal.
And this is the underside after removal, showing the connector connections and microswitch solder joints, all coated in a thick layer of brake-cleaner-resistant conformal coating of some type.
I couldn't really see much of the joints through this dark brown coating, but did think I was observing a little more movement than expected - when waggled gently - of the connector relative to the board. Cleaned away by scalpel a few bits of the brown coating to get a better look, and one joint was particularly grim. It's the earth connection, which goes to the door open microswitch and some other places...
Here's a very brief video of it being waggled:
20200910_155143.mp4
I swapped the new microswitch in as well, as it made no sense not to.
Everything's pretty much back up together again now, but only 3 out 10 rivets replaced, and no door card yet. I will await feedback from the owner on both types of misbehaviour before finishing it off, I think.