Fuse Keeps Blowing? Get Help Now!

Okay, so here's the problem...

First of all, I want to mention that I'm not involved in the automotive industry, so I don't have much knowledge about it. I've also browsed through the forum posts, but I haven't found anything relevant.

In my Seat Ibiza TDi, manufactured in 2000, with an engine power of 81 kW (110 hp), the fuse number 8 in the fuse box keeps blowing every time I turn on the ignition.
According to the owner's manual I have in the car, this is the lambda sensor fuse. (However, as far as I understand, TDI engines don't actually have a lambda sensor.)
Today, I had a friend run a diagnostic test on my car, and it showed 5 errors.

1) 0502 Valve, intake manifold switching - interruption/short circuit.

2) 4625 Turbocharger boost control valve - open circuit/short circuit.

3) 45B9 Exhaust gas recirculation valve - open circuit/short circuit.

4) 4626 Pressure difference in the control system.

5) 4632 Quantity setting device/Fuel injection pump, at maximum setting.

However, I should also mention that the fuel injection pump was replaced about 6 months ago.
Yesterday, we tried installing a new fuse several times. The motor started a few times, but after a few seconds, the fuse blew again.
Today, however, the fuse blows as soon as I turn the ignition on.

I spoke with some mechanics to get an idea of what might be causing the problem, and they suggested that there might be a corroded or broken cable somewhere. However, I'm not sure where to start when it comes to checking the car.

I would appreciate your helpful answers.
Thank you in advance.

Hello bay-pass!

According to the wiring diagram from December 2001 and May 2002 (I unfortunately don't have any other versions), fuse 8 is responsible for the exterior mirror heating. After this fuse, relay 99 switches the power from the driver's side and passenger's side door control units to the mirror heaters. (Fuse 8 is 5A and beige in color?).
First, turn off the mirror heating switch (located in the driver's door).
If the fuse (after being replaced) doesn't blow, then the problem is either in the wiring or in the door control modules.
I hope the wiring isn't different for models from the year 2000.
The motor should continue to run even with a blown fuse!
A potential source of error could be a damaged cable, creating a short circuit to ground.
After I receive some feedback, I might be able to offer more tips.

best regards

tdi-erwin