8 yrs of perfection but, last week went on a trip, check engine light came on amber with reduced performance note. Car was running fine. When got around to checking things out, I found the air intake tube loose at connection to throttle body. Tightened it, all well except the light won't go out even after a battery disconnect. Do i need an OBD2 tool to reset it?

 

I think certain check engine/MIL/CELs will go out after a defined number of drive cycles, but that's difficult to know without determining the code with a scan device.

 

This is correct, as I had the same CEL symbol come on the week before last. Car went into shop for another problem, (Blower fan failure) and when they read the code for the CEL, I was told it was one of the codes that will persist for about 7 starts, then disappear if the underlying condition is no longer there. This actually panned out over the following week, in fact I have had the CEL on again, and again it disappeared. So I'm keeping an eye on it at the moment.