Hi ClubPolo

I'm having an issue with my 2009 Polo 9n3 match that I'm really hoping some of you smart people can shed some light on.

Basically, this winter my car has developed the ability to unlock itself whenever it likes, whether I'm around or not. Whilst driving I've had the CL unlocking the doors repeatedly, and when it's been really bad, both the passenger and drivers side windows will drop. This is the 3rd winter I've owned the car and the first time it's had these issues.
I'm fairly convinced that it gets worse when it's been raining lots.

I'm no mechanic, but I've been googling the issue non stop to try and work out what I need to do - I've had both door cards off but didn't spot anything to my untrained eye.

I took it to an auto electrician this week, who checked the wiring and a pillar connection in the drivers side door. They found some corrosion in the plug of the window regulator (6q1959801f) which they've cleaned but the issue hasn't gone away. They suggested that the next step would be replacing the unit but I'll have to source my own. (They gave me the part number for the Y variant, but having been inside my doors I know the car has the Q version fitted...)

I've seen suggestions that it could be the microswitches inside the lock module itself, but I'm unable to get this deep in to the car door myself. This also seems like it'll be quite expensive to get fixed, and i cant check part number from the outside.

Basically, does anyone have any ideas? Could the drivers window regulator really causes the car to unlock and lower both windows, or is that a red herring?

For now, I've been removing the fuses for the windows and CL so that the car doesn't get raided or soaked, but it'd be really nice to lower the windows in Summer, and to trust the CL to not offer up the cars contents to any random passerby!

1 hour ago, JPBristol said:

Could the drivers window regulator really causes the car to unlock and lower both windows

Yes, because the key position information from the lock module goes first to the window motor (to enable the 'lower or raise both windows via key in door lock' function).

From the window motor it then goes onward to the central convenience module above clutch pedal for locking system control.

If the moisture ingress has caused circuitboard damage in the window motor module, this input from the lock module may get corrupted and cause both locking and window activation without any real key input.

I think I have a suitable 6Q1959801F unit that could be tried if you fancy an eastward trip along the M4 sometime.

Hey Pete, thanks for the reply (I was hoping you'd see it and have some knowledge to share!).

That's interesting to know that it could be the issue then... I've been super busy with work the last week so haven't had a chance to look in to anything more yet. There has been one new development though, when I put the fuses back in now, I can no longer control the passenger window from the drivers side door. It does however still work from the passengers switch, and when I hold the key in the unlock position in the drivers door.

I need to give the garage a call still to let them know the issue isn't resolved, but I'm pretty sure they'll just want to fit a new part. It's proving to be a really annoying issue to test as it's so intermittent, and the only way I can test it really is to leave it for the day while I'm at work and see if I come back to an unlocked car or not, which I don't love!

Comms problem between motors tends to be corrosion of A-pillar connector contacts, if the bellows have ever been removed and not well refitted.

In this case I guess there's also the possibility that the LIN connection pin at the driver's side motor connector may be corroded due to the observed water ingress.

Hey Pete, sorry to lean on you so much for this, but I'm having a hard time working out what's what with this issue.

The auto-electricians I went to are adamant that the dealer specified that 6Y1959801 is the right part for my polo, but as shown in my original post, the part currently in my car is definitely 100% 6Q1959801f. Are these interchangeable? To my eye, they look like they'd mount differently, and the Y version definitely has a 2 connections whereas my current regulator has only 1 connection (and no sign of another unused wire hanging around).

On the symptoms front, the last time I had the fuses in for a test, I couldn't control the passengers side window from the drivers switch, but then later on I could, but the drivers side would only go down an inch per press, then the passenger window started trying to go up again and again so I removed the fuses. Car continues to unlock itself occasionally, but this is harder to test. Either it's haunted, or there's definitely something going on!

I had a look at the A pillar connection and the boot but didn't spot anything obvious myself. The auto-electricians say they checked the following:

Investigate reported fault

No fault codes in any systems
Check drivers door loom, all ok.

Strip driver door card. Gain access to door control module.

Check feed earth and signals, all ok.

Remove module.

Upon removal locate corrosion on plug. Clean up corrosion.

1 hour ago, JPBristol said:

re these interchangeable? To my eye, they look like they'd mount differently, and the Y version definitely has a 2 connections whereas my current regulator has only 1 connection (and no sign of another unused wire hanging around).

Not readily interchangeable, if at all. As you rightly say, the connectors involved are completely different, so bodgery or loom replacement would need to be done to change from one type to the other.

I'll start a private message conversation with you so that you can share the vehicle VIN with me without publishing it. I can look up which part was factory fitted, but I think in 2009 it's highly likely that the one you see installed currently is original and correct.

Ok great, thanks for confirming that the parts aren't interchangeable, I was starting to feel crazy talking to the garage! Not sure I'll be returning to this one in a hurry...

I'll DM you the VIN now.

My current plan is to source a used replacement that matches the part number in the car, and it looks like I could swap it over myself so long as I can find somewhere safe with enough space to work.

Armed with the VIN, I was surprised to find that VW did indeed record this car as having been built with 6Y-series window motors.

Not sure I believe it though.

Maybe check to see what you find under the passenger door card as a first step to de-mystify this, unless you know already?

It could be that someone has replaced driver's side door loom and motor, I guess, and I think it would 'play nicely' with a 6Y1959802 passenger side unit.

If you do elect to buy a secondhand driver's side motor to try, match the line that starts VW240... as well as the main 6Q1.959.801.F

If you fitted a unit with SK250.. or SK258.. as that second line on the part number label, I'd expect up and down to be reversed relative to switch inputs.

Don't throw away the old unit if replacement does fix things, please; I'd give you a little cash for it.

Happy to help over here in Highworth if you want some hands-on assistance.

53 minutes ago, Pete1 said:

with the VIN, I was surprised to find that VW did indeed record this car as having been built with 6Y-series window motors.

Not sure I believe it though.

This car is a gift that keeps on giving! 🥲

51 minutes ago, Pete1 said:

Maybe check to see what you find under the passenger door card as a first step to de-mystify this, unless you know already?

It could be that someone has replaced driver's side door loom and motor, I guess, and I think it would 'play nicely' with a 6Y1959802 passenger side unit.

The passenger side is fitted with what I assume is a match to the same family as the drivers side: 6Q1.959.802.E.
Added a photo of the passenger door opened up. Unfortunately, I didn't have the presence of mind to take a nice wide photo of the drivers side door to match.

Thanks for the flag on matching those secondary numbers - I'll see if I can find a like-for-like match, did you say you might have one?

Once I have the part I may have to take you up on that offer if I can't find a suitable place to do it myself (roadside parking annoyingly!)

I thought that's what would be on passenger door.

Date code consistent with vehicle manufacture date too.

Yes, I have a suitable 6Q1959801F here. Would be same price territory as ebay ones, but known good (repaired by me).

I'm having the same problem. If I unplug the door lock and unplug the window motor, I still get the random central locking unlocking itself. Was thinking comfort control module (bcm).

Any help

@jamesm what year of car are you talking about? And is it a Polo?

It's 2009 fabia. Iv been told there is another module possibly a ccm.

Mk2 Fabia and lots of other Skoda models with the same 'straight across the gap' bellows design suffer cracked and broken wiring near the A-pillar 28-way connectors, almost all of 2009 vintage probably have broken wires if never repaired. Could be either or both sides of the car.

The BCM, above accelerator pedal has virtually nothing to do with the locking system and nothing at all to do with the windows.

The Central Convenience Control Unit (high above clutch pedal on manual RHD cars) does control the locks, but almost never is the source of any trouble.

Thanks. Have tried every wire in the driver's door. All were continuity tested and all seemed fine. Is puzzling me

Try passenger door next. Visual inspection under the bellows is probably sufficient.

Does passenger front door have a hole for a key to lock/unlock it from outside?

If it does, passenger side window motor might be a suspect. Might be even if it doesn't.

Edited 30 March Mar 30 by Pete1
Other thoughts

Passenger door does have a key lock yes. It doesn't operate the central locking tho. I have everything plugged in apart from the driver door electric window motor. This is stopping the windows going down. Still getting the random central locking clicking while driving. Could does it once a day or for a solid 10 minutes while sitting parked or driving

Maybe disconnect passenger front window motor too and see if things settle down then.

Actually, much easier to just pull its fuse instead. That should stop it sending any spurious lock/unlock stuff to central convenience control unit, if it is/was.

I'm going to disconnect the window motor in passenger door, reconnect driver window motor and see if driver window still goes down. I'd rather get to the bottom of it. Do you know it there more than 1 module. A comfort control module and another 1? I'm not at the car again until Wednesday so can't check.

Yea could remove fuse for windows and see if it still trying central locking

9 hours ago, jamesm said:

Do you know it there more than 1 module. A comfort control module and another

Yes, see my reply a few posts above that starts "Mk2 Fabia".

Won't be either of these, I'm almost certain.

Thanks for your reply Pete. I will do a few more checks I the next few days and let you know anyone updates or developments

@jamesm Did you ever get to the bottom of this issue? I'm having the exact same problem with my 2008 Skoda Fabia (windows rolling down, and intermittent cycles of locking/unlocking).