Focus Zetec s Engine light

[spurswes]

My engine management light came on and basically its the flaps in the manifold sticking.But when I started it yesterday the light had gone out. I thought you got to have a computer to make the light out. Can anyone shed any light on this??  Thanks.  It an 09 plate

[isetta]

depends how the makers programmed it. for some faults it stays on until turned off by plugging in a code reader/reset tool. with some faults it will go off if the system does not detect the same fault occurring within a certain number of times you drive it as the system kind of thinks, it has not happened again for a few days, it must just have been a fluke / one off that the fault was signalled.