RomRaider

I'm unable to disable these DTC's for 2002 UDSM WRX:
- P0447 EVAP VENT CONTROL CIRCUIT OPEN
- P1400 FUEL TANK PRESSURE SOL. LOW

I read the original ECU flash, with Romraider disabled these two DTC's and flashed the modifiend ROM back to the ECU.
To verify that the flash was successful I read the ECU one more time and yes these to codes have the status "disabled", but when I read the fault codes, these two errors are stil present.

Tried to modify the ROM with ECUFlash, but the same thing happens.

Any ideas why? Somewhere I read that not all DTC's can be disabled in the 02-05 ECU, is that true?

is it possible that the fault codes were already flagged as active when you read the rom off the car? try downloading the stock rom from the list here - remove the codes and flash it on:
https://www.romraider.com/forum/viewtopic.php?f=35&t=7591