How the check engine light (CEL) gets illuminated

[franklin.bowen]

I just talked to a service guy at Subaru and he said:

Every time you start the car, it does a full diagnostic and if any
sensor is out of its valid range the CEL will be illuminated. The CEL
does not store its state between car starts.

I asked because our light came on. Since we were too busy at the time,
the nearest dealership is 1.5 hours away, and there were no noticable
signs of distress from the car, we let it go. A couple weeks later it
turned off.

I thought maybe they programmed the CEL to turn off after so many days
but that is not correct since the state of the CEL is never stored and
determined upon every start of the car.

HTH someone, some day.

 

[TG]

Your service guy is wrong, go to the OBD II web site and learn a little
about the system....remember, the Subaru from '95 on uses the SAME
diagnostic system as every car sold in the USA from '96.I am assuming you
are in the USA. TG

 

[franklin.bowen]

I assume you mean this:

http://www.obdii.com/background.html#Check Engine Light

Ah crap! Why did you have to spoil my simple world? ;-) Oh well, the
light has been off for months now so I will just play the waiting game.

Thanks!