It's taken me longer than it should to get around to doing this, but:
If you have a late production Skoda Favorit (or similar derived model like the Forman pickup?) with the Mono-Motronic fuel injection, there is a 5-pin diagnostic connector at the back of the engine bay hiding behind the charcoal canister.
It's a 5-pin JPT connector, and the matching housing should already be in place as a blanking cap; so you can pull the rubber plugs out of the back of it and fit JPT terminals yourself.
You can fit your own wiring to this and run it to an OBD-2 style diagnostic link connector inside the car, so that you can use a compatible diagnostic unit to read codes from the ECU without having to track down the magic mystery adapter leads.
You will not be able to use the generic ELM-based OBD2 readers.
The Mono-Motronic system communicates over K-line and L-line, using KWP-1281. Use something like a Ross-Tech HEX-V2 and VCDS; in which case, the correct variant to feed to "auto-scan" is a Mk2 Polo, or Type 86C.
There's also other generic tools out there, you specifically want something that communicates via K-line; your mileage may vary.
Pinout
| Skoda DLC 5-pin | Description | OBD2 DLC 16-pin |
|---|---|---|
| Red | +12V Battery | Pin 16 |
| White | Chassis Ground | Pin 4 |
| Black/White | Diagnostic Ground | Pin 5 |
| Black/Green | K-Line | Pin 7 |
| Yellow | L-Line | Pin 15 |