I've just disconnected the battery in my 2002 Octavia for the 1st time in the 8 years since I bought it new, but the convenience coding system isn't working and so the radio (Skoda Symphony) is now stuck in safe mode.

I know I can't use VCDS to fix that, but I'm puzzled by the radio serial number. A VCDS autoscan shows that the engine and instruments both know the chassis number as well as another number which is SKZ7Z0B1604733. I had assumed that this was the radio serial number, and it made sense that the ECU and Instruments might need to know that as part of the convenience coding system.

BUT, the radio itself and the sticker on its manual both have the serial number SKZ2Z3B1421991. That's similar enough that it makes me think they're both radio serial numbers, but completely different...

Is the number on the VCDS autoscan a radio serial number? And if it is, does anyone have any idea why the car knows about a different radio to the one it's had from new? I'm just wondering if the radio got replaced in the factory or something, and whether the instrument cluster might still have stored the code the original one hence the convenience coding not working...

Thanks very much,

Alan

Is the number on the VCDS autoscan a radio serial number?

Think I may have answered my own question - I think the number on the VCDS scan is the immobiliser serial number, and just happens to have the same format as a radio serial number. I think this must be the case because the same number is on the sticker with the scratch off panel for the immobiliser PIN number which came with the car's keys.

I've no idea why the convenience coding wouldn't work though... Thankfully the main dealer I bought the car from were great and gave me the radio's PIN number without charging me at all.

Here's an example from my old Octavia...

Address 25: Immobilizer Labels: 1K0-920-xxx-25.lbl

Part No SW: 1Z0 920 842 C HW: 1Z0 920 842 C

Component: IMMO VD1 1612

Revision: V1612036 Serial number: SKZ7Z0F3880448

...that would be the serial number of the immobilizer (often called immobilizer id).

Address 56: Radio (J0506) Labels: 1T0-035-680.lbl

Part No SW: 1Z0 035 680 A HW: 1Z0 035 680 A

Component: RNS-MID H04 1024

Revision: AB001001 Serial number: SKZ6Z7H9111142

...that would be the serial number of the Radio/Nav.

As you can see the serial numbers differ between the modules, even though they are similar in this case.

Here's an example from my old Octavia...

Address 25: Immobilizer Labels: 1K0-920-xxx-25.lbl

Revision: V1612036 Serial number: SKZ7Z0F3880448

...that would be the serial number of the immobilizer (often called immobilizer id).

Address 56: Radio (J0506) Labels: 1T0-035-680.lbl

Revision: AB001001 Serial number: SKZ6Z7H9111142

...that would be the serial number of the Radio/Nav.

As you can see the serial numbers differ between the modules, even though they are similar in this case.

Thanks very much for the reply, and yes it's the immobiliser serial number/id that I was seeing. What had confused me is that my autoscan doesn't include address 25, and my address 56 scan doesn't report a serial number at all, so I was just getting a single SZK... serial number, repeated in address 1 and address 17. Knowing that radio serial numbers start SKZ, and knowing that the instrument cluster remembers the PIN number for the radio had left me thinking that it might be a radio serial number stored in the instrument cluster and engine. I then realised that the immobiliser serial number was the same format, and that made a lot more sense!

You can on some of the radios get the serial number from the radios measured value channel 81.

Saves taking the radio out to find out

Correct, the very old ones didn't show it in diagnostics. The ones in the middle had it in MVB 081 and all the more or less current ones have it in the Control Module ID.