Fabia: Low Fuel Rail Pressure - Troubleshooting

Good evening.

I have a Skoda Fabia 1.2 TDI manufactured in 2012 with 75 horsepower, and I'm at my wit's end. About a month ago, while driving home, the first injector failed, causing only diesel to leak out (with a lot of white smoke).
Following that, I purchased a refurbished injector from Diesel Technik Biberach and installed it. After that, the engine worked again to some extent, but unfortunately, I've also had the problem of low rail pressure ever since. Then, I started replacing other spare parts: the rail pressure sensor, the rail pressure control valve, the quantity control valve, the fuel filter, the fuel filter near the tank, and most recently, I replaced the other two injectors because one had a higher return flow than the first one. Now, with the new injectors, the first injector has significantly more return flow than the other two new ones. I don't know what else to do.
VCDS is available.
The engine idles roughly and makes a slight knocking sound. However, the "rail system pressure too low" error only appears under load, when the difference between the target and actual rail pressure becomes too large. The maximum rail pressure indicated by the sensor is 77,000 kPa.

Hi,

Where is the automatic scan function? Customer support for VCDS is available; otherwise, please contact us using the following methods:
https://shop.dieselschrauber.org/en/obd-support-key-p-112.php

Best regards, Rainer.

Is compression okay?

The compression is okay, as we initially suspected that the connecting rod might be slightly compressed due to the diesel knock.
Here's the Autoscan results.

Hello,

It's a shame you chose the wrong VCDS provider...

Why don't you check the car scan?

If the fuel rail pressure is too low, no fuel will be injected, which means the car may not start or may run poorly.

If I were you, I would check if the rail pressure regulation is working correctly and, if not, what the cause is. Perhaps the "new" injector has an excessive amount of oil leakage?

Since faulty injectors can also damage the pistons (which would then produce white or blue smoke), I would first perform a compression test.
If the car is now running smoothly without any unusual noises, then the piston is likely in good condition.

Best regards, Rainer.

The car is running as described so far, but unfortunately, the error always occurs when the target pressure is higher than the actual pressure.

Okay, I will translate the text you provide. Just paste it here and I'll give you the English translation.

Okay, thank you. I've already checked the compression, and there's no blue or white smoke visible either. I suspect it might be due to the rebuilt injectors.

My question is this: A friend of mine works at Volkswagen, and he mentioned that they sometimes encounter situations where, according to the inspection reports, the reconditioned injectors are supposedly fine, but they still don't work.

A software update then fixed the issue. I have a Bosch service center nearby; should I have them check the injectors there, or should I just replace them with new ones?

What are the return flow rates at the injectors?

Somewhere, there was still a better picture or description...

The return quantities vary quite a bit.

I got a bit of a fright; I thought those were actually measured values.

Disconnecting with reference to:
/viewtopic.php?t=28779&highlight=backflow_volume