ECU and Engine Management Light

[SAMXPJ]

Does anyone know how the ECU memory works with regard to holding on the various fault lights, for example if I pull my ECU how long would it need to be out of the circuit before it lost the memory or is there a relay type function somewhere? I am assuming the fault is now cleared and no further faults exist.

[p fandango]

not all faults are automatically cleared like that, you many need to hook up a reader to clear them if you've solved the problem. Leaving the ECU out over night will clear others

[SAMXPJ]

Yes I know BUT WHY, what system do they use to enforce this, there needs to be some form of electrical energy within the ECU or a mechanical relay somewhere along the line. Is there an electical cell in the ECU?

[SAMXPJ]

I have just been told that it works in the same way as a computer memory stick ie magnetic ferric rings acting as gates so it seems the main stealer rules!