When you turn ignition to "On" position the engine computer is supposed to run some checks and turn on all the warning lights such as Battery and etc. and then they are supposed to turn off once the engine is running. What he is saying is that during this check, the check engine light does not light up. He is asking what does this mean? Does that mean the ECU is fried and no good? In other words, what he is saying is that if he were to disconnect an engine sensor such as the MAF or IAC valve, he does not get a check engine light on and when he goes to read the codes, the scanner says there are no codes. What does this mean? ECU fried?