Do codes that trigger the check engine light fall into two groups? One
group behaves in such a way that if triggered, the CEL remains on and
has to be reset manually. With the other group, the CEL will turn off
automatically once the problem is fixed. Does this make sense?
Examples?

 

The CEL will normally turn off after three consecutive passess of the
initially failed test. Some tests require certain conditions to be met,
so they may not run every time the vehicle is driven.

 

The CEL will normally turn off after three consecutive passess of the
initially failed test. Some tests require certain conditions to be met,
so they may not run every time the vehicle is driven.

 

The CEL will normally turn off after three consecutive passess of the
initially failed test. Some tests require certain conditions to be met,
so they may not run every time the vehicle is driven.