P0171 and P1241

Hi, I have a 2001 GT Legacy twin turbo Legacy, chassis number BH5-183269 model BH5D5CT engine EJ206DXDBE

When I go on half or full throttle I get error code P0171 (System too lean bank 1) and error P1241 (2 stage twin turbo system single)

Apart for the slight delay of getting power I do not loose power or acceleration. The error code goes when I switch off an on the car after about 5 minutes.

Is there a checklist I can use to troubleshoot the error codes.

Thanks

Sent from my SM-N960F using Tapatalk