Sporadic emergency mode SEAT Leon

I've been driving an ARL for 82,000 kilometers. Unfortunately, it has been repeatedly going into emergency mode at irregular intervals since March.
Initially, there was a daily emergency operation. These messages were read after a "Wo".
Relay, low heating power, intermittent short circuit.
18080 Fan control 1: Short circuit or open circuit to ground.
17932 Fuel pump relay - short circuit to ground.
19461 Relay, high heating power, occasional short circuit.

The friendly person suspected: Engine control unit (ECU) failure.
I sent it to Hitzing&Pätzold, and they spent a week trying to figure it out, but they couldn't find any errors.
Reinstalled, it worked fine for 2 months, then the lamp started acting up again.
The wiring harness near the engine has now been replaced. It was quiet for 1000 km, but then the light came on again.
Then, again, nothing for 1500 km.
Here we go again, the problem is back. But this time, no light on and no entry in the control unit.
(Maybe it wasn't an emergency operation after all...)

Symptoms:
Sudden loss of power while driving, maximum speed approximately 100 km/h.
After restarting (i.e., starting the engine), everything is working fine again.
(Especially pleasant when you're overtaking.)

Do I have to invest 1000 euros in a new control unit, or could it be something else?

I am grateful for any help!

It sounds more like a cable problem: Please check the wiring that supplies power to the components listed in the error memory. Sure, including fuses, etc.

You definitely need a wiring diagram for that.

Best regards,
Guste.

Yes, thank you for the tip, using a cable was also an idea I had.
I've now discussed with the that if the problem occurs again, I will go directly to the workshop without resetting anything, so that they can access the current data and measurement blocks. Maybe this will help us move forward...

Best regards, Achim.