Hi Vlad,
There are two issues that can cause this, one being that you have a stray voltage signal feeding into one of the sensor 0V's, that pulls up the 0V, this means that the ECU can't read the signal correctly as it needs a differential between the 5V+ and the 0V to do so.
The other cause of this is that the ECU has been reverse wired and this has damaged the reverse polarity protection. If this is the case, then the ECU needs to be repaired at one of our service centres.