Error reading failed

Hello, I have a 1995 Volkswagen Golf Variant with a 75 HP diesel engine, and it's broken. Well, sometimes it works.

Sometimes (almost always), my preheating light blinks, and then the engine doesn't start.

After several attempts and a few taps, the light no longer blinks. Then, it starts working.

I know - reading error codes, but that's exactly my problem, the PC doesn't recognize it.

golf, as you know, sometimes the problem can be a faulty connector, or it could be something else.

Where is the motor computer located? I've been to many workshops, but none of them could read the data from it.

What a mess. Does anyone have any advice?

Thank you, Matti.

ps: I don't have a 109 in the vehicle, is that normal? Or did someone just remove it at some point?

"Is it a different type of connector? However, the contacts look the same from the bottom as they do on the 109 model."