Check Engine Light
What triggers a CEL....a single incident or an accumulation of faults to meet a pre-programmed threshold? Have a 2013 F-150 5.0 V-8 with 120K miles. For the last couple of weeks it's been kinda rou...
Forum Discussion
To answer your original question, the CEL comes on when conditions detected by the computer call for it to be turned on. When those conditions are no longer present for a set amount of starts or miles, the light goes off.
So if the code came up that the #7 was misfiring, and the next time the light went off, that means the Autozone person reset the code, or the computer no longer thinks the #7 cylinder is misfiring.
A scan tool is as cheap as $30, and handy. Everyone should own one. I never would have made it to 218K on my last truck without one, and people ask me to scan their vehicles with it all the time.
So if the code came up that the #7 was misfiring, and the next time the light went off, that means the Autozone person reset the code, or the computer no longer thinks the #7 cylinder is misfiring.
A scan tool is as cheap as $30, and handy. Everyone should own one. I never would have made it to 218K on my last truck without one, and people ask me to scan their vehicles with it all the time.
