question ecu stored codes even when light is off

[Jtuned S13]

i only ask cause every time i want to scan my car im on the freeway...as soon as i can get off the effing light turns off ...i dont have a scanner but im going to buy one only if i can pull codes even though the mil isnt on...is it possible or do i have to do it when the dam thing turns on??what the deal

i have smog in 2 months that is why im stressing

[cotbu]

Does the ecu store codes, when the light is off? Yes!