My 2004 Octavia has finally reached the end - too many things needed for the mot, and too many little jobs keep needing to be done. The remapped engine is still pulls well at 273K though! So I have just bought a 2015 187k 2.0tdi to replace it. All seems good. However, I noticed some modification to the wiring around the OBD port area. Does anyone know what this might be for? I've not disturbed it so it's not clear where each wire is coming from/going to. The blue wire looks to come from the main harness towards the port but it is then not connected to anything. Likewise the yellow and the red wires look to come from the main harness towards the port? but then each have one of the 'big plastic connectors' (I don't know what these are) and then both appear to be joined to a single black wire that disappears up into the dash somewhere. Most of the service history is main dealer, but I wouldn't say this looks to have been finished very professionally. The port seems to function fine with VCDS. Finally, is there a piece of trim missing here? I didn't remove any.

23 minutes ago, SteveOctavia19tdi said:

'big plastic connectors' (I don't know what these are)

Fuseholders. Each has a plastic cap that hinges open to reveal a mini blade fuse.

The big plastic connectors look to be aftermarket blade fuse holders so I'd guess that it's probably retrofit wiring for a dash cam or phone charger that's not been fully removed.

Thanks. So if each is fused I'm guessing the red is maybe permanent live and the yellow switched live, and under the red tape they are not joined to anything. Maybe the black wire coming from above is an earth. Not sure about the blue wire though. I will investigate further!