[N*Caddy]

Gheorghe,
Have you removed the head unit (radio) from the car, or have you done any under dashboard work? The U code is network failure. I don’t remember the pins (I have the schematics somewhere) but start by making sure the connector is plugged properly in the back of the HU. If all tight you might have a failing HU (the chip). Not a big issue, you can find a replacement HU with less than $50 on E-bay, just make sure is for your year and model (although they look the same they are TOTALLY different inside).

As for the fuel pump issue, yes the pump will not trigger any code but will get the service engine soon light on. The simplest way to check the pump is just to push the fuel line service valve (Caution! high pressure gas, no flames, protect your eyes). If sprays with key in ON position (I mean really really sprays) then the pump is likely to be OK.