I posted recently asking about where to find the siren on a 2012 Skoda Superb, I had trouble with the alarm going off a few minutes after locking, then it stopped making any noise, figured it was the siren battery, 12 years seems way past expected life. Thanks to help I found it - below windscreen, awful to get at. Anyway, I got it out... 

 

First I managed to get it open and confirmed battery was dead - it read 1V (6V battery). I sourced a replacement battery (reads good 6V+) and soldered that in, but the siren remains dead, still doesn't chirp on lock/unlock, doesn't sound when alarm triggered. So I bought one on aliexpress. It looks new and genuine.

 

The original part is 1K8 951 605B, the replacement (which had several part numbers on the listing including this one) is 1K0 951 605C. I believe these to be compatible...

 

But when I connect the new siren, it just chirps constantly roughly every second. When I lock/unlock or turn ignition on, it makes more strangled chirping sounds, but doesn't sound quite right, continues to chirp every second, and it does NOT make a loud siren noise if I trigger the alarm.

 

I have a cheapo obd reader which seems to talk to the car ok but says there are no errors stored. Vehicle battery is good.

 

Has anyone seen anything like this? Is there something that needs doing to tell the car about the different part, or could the new siren be faulty, or could there be a problem elsewhere in the alarm system?

Most likely your cheap Chinese replacement is not so genuine...

Too bad, since somewhere in the near future I will have to replace mine too.

 

Edit: There was already an older topic about this siren, which also shows its location:

 

Edited 16 November, 20241 yr by andrehj

Mine is indeed there, took me an hour of gentle prising and rubbing in soapy water just to get the plenum cover to start to move, but my siren was even more awkward because it is not attached to that metal brace pictured on that other topic, it is mounted on a bracket which attaches over the top of that air inlet, and there is another plastic cover screwed in over all of that, which is extremely fiddly to get out as it seems the car was assembled around it, and it also has the wiring for the heated windscreen attached to it, which is a very flimsy thing attached with tiny screws. 

My Ali-Express one did not work either, VCDS revealed that the ECU was not able to communicate with it, a generic OBDII reader does not interrogate the Canbus modules, all it can do is read and reset generic OBDII codes held in the main ECU, these are emissions or safety related eg EGR, ABS problems etc.

31 minutes ago, J.R. said:

My Ali-Express one did not work either, VCDS revealed that the ECU was not able to communicate with it, a generic OBDII reader does not interrogate the Canbus modules, all it can do is read and reset generic OBDII codes held in the main ECU, these are emissions or safety related eg EGR, ABS problems etc.

Thanks, I suspected my reader was not telling me everything. Where else did you source one from?

It was over 5 years ago, I think I just disconnected it and removed it from the installation list using VCDS to stop the no comms fault codes showing up.

There is also this thread about replacing this siren in the Octavia section:

Does have quite a few posts, but also no references to working, cheaper alternatives.😒

Edited 17 November, 20241 yr by andrehj

For everyone's info - I bought another used unit on ebay, primarily to prove if the fault was in my chinese unit, or elsewhere on the car. The used one (also the newer part number 1K0 951 605C) works perfectly, so the aliexpress one is definitely dodgy.

 

I don't know how much life I'll get from this used unit but I know how to open them now so I will replace the battery in this one when it is needed. I am pretty sure now that my original had died in some other way other than just the battery failing.

3 hours ago, SuperbDP said:

For everyone's info - I bought another used unit on ebay, primarily to prove if the fault was in my chinese unit, or elsewhere on the car. The used one (also the newer part number 1K0 951 605C) works perfectly, so the aliexpress one is definitely dodgy.

 

I don't know how much life I'll get from this used unit but I know how to open them now so I will replace the battery in this one when it is needed. I am pretty sure now that my original had died in some other way other than just the battery failing.

Is the only way to know the siren battery is dying is if it goes off by itself just before it dies completely? Mine is 12 years old too, and I'd rather not it does silently then not go off if a yobbo smashes a window etc. 

@SuperbDP Thanks for the feedback. Too bad you haven't found a working one at Ali though... Mine is also 13 years old, so I might need a replacement in the near future as well.

When mine started going off soon after locking, I googled it and consensus seems to be this happens when the battery is failing - but the siren still works. Mine then stopped making any sound. I don't think it normally then progresses to stopping altogether, I think mine died for a different reason. The battery was indeed dead, but I replaced it and it still didn't work. But given these things have a stated lifespan of 6 years I think replacing it at 12 or more is a reasonable course of action before it starts causing problems. The used one I now have installed is from a 2015 car, so I may be replacing the battery in that in a couple of years... If you have a vcds reader, the car does record a low voltage error on the siren apparently, which is another way of spotting the problem, but I only have a cheap obd reader and that doesn't pick that up. 

One more follow up for anyone considering a replacement from aliexpress - when I bought mine, I considered it a risk still worth taking because I didn't think returning something shipped from China would be an option - but it is. I initiated a free return when I found it was an option, and was sent a prepaid royal mail label addressed to a handling centre in the UK. As soon as it had been scanned by royal mail, my refund was issued. So I would say even though mine didn't work, if you need one of these, it's worth giving aliexpress a try because you CAN return it if it doesn't work. Some of them must work... and my car continues to be ok for now with the used one installed.

Edited 4 December, 20241 yr by SuperbDP

2 hours ago, SuperbDP said:

Some of them must work...

 

We have yet to hear of one!!!!!

 

They work as far as the manufacturers and sellers are concerned because people pay them money for them!