Check Engine Light 2004 Sonata 4cyl

I purchased my Hyundai used from CARMAX in Oct 2006 and six months after the check engine light came on.  It goes off and on.  I used fuel line cleaner and this seemed to help for a while.  I want to take it to the dealer as stated in manual, but read this as costing a lot of money for an unidetifiable fix since it is intermittent.  Looking for genneral advice.  Thanks.

Whenever a light goes on, it stores a code, and even if goes back off again, the dealer can read the stored code.  If the light goes on, though, take it to AutoZone and they will read the code (but it's gotta be on I think).

If the car is less than 60,000 miles, you're still under the bumper to bumper warranty, so reading the code should be free.
 
I bought my Elantra brand new and it threw codes on and off for a while starting just before 10,000 miles; they finally isolated it to a defective valve in the evaporative emissions system.  It was kind of a pain taking the car back repeatedly but in the end all the visits were covered under warranty.

Its not under warranty.
The warranty is only applicable to the first owner... I found this out firsthand.
Bumper to bumper, powertrain, rust and corrosion, all thrown out when the vehicle is traded in.

Thanks for the advice!

I have been out of town and will call to see if it is still under warranty.  I asked when I bought it and they said it would transfer...we will see.  If not I will take it to AutoZone or equive and post the code here.

quote:

ORIGINAL: Joshewuhh

Its not under warranty.
The warranty is only applicable to the first owner... I found this out firsthand.
Bumper to bumper, powertrain, rust and corrosion, all thrown out when the vehicle is traded in.

 
Not so. The 5 yr., 60,000 mile warranty goes with the car- it is transferable. The 10 year powertrain warranty is not transferable (with some exclusions for family members).