Ocationally when I start my car now after not driving it for a weeka dn having a flat battery, the CODE illumintes on the dash. Can anyone enlighten me please on what this means. It doesnt happen all of the time and will stope if I turn off the ignition and restart it. I am also currently using the red key all the time to start.

Any help apreciated.

its the immobiliser warning light.it should go out after a few seconds.
when you kow the battery is flat try to wait tillthe light goes out before cranking