Does the check engine light have to come in order to throw a code to a code reader?

If it is an OBDII system, codes can be read before the code is set. There is a pending code reading area that lets you know if part of the parameters are met for setting the code. So a scan tool on the OBDII system can read codes light on, off, or hasn't come on yet.

Thanks I was told by the guy at autozone. That if the check engine light wasn't on, a code would not have been given.

not all codes turn the light on.


hey,way too old how ya doing sent you some info on the honda did you get it?
t-rex