Volvo: ETS lights with P1603 Code on Volvo S70, scanner system, volvo s70

Question
Hello,
ETS lights comes on and off randomly and with ODBII code reader it reads P1603 and I think it has something to do with EEPROM malfunction. And also my ODBII unit reports that CAT is not ready, EVA is not ready even after I've erased the error codes. With these problems the gas mileage drop to about 200 miles per tank from 350 miles on highway. Oh the same error code comes back on the next day after the erase. HELP Please...
Thanks

Answer
Stephen,
The vehicle needs to be hooked up to Vida or Vadis to see what parameters are showing for the code you have. However I feel that a possible download of software to correct the faults that you have are needed. You need someone that has the scanner system to read it and then download the new info.