I just bought a 1993 Diamante and It has a few problems. I plan on making it a winter car. I an getting horrible gas mileage but fuel is not leaking on the ground. My check engine light is not on but I was wondering if parts could go bad and not necessarily throw the CEL. Unfortunately I do not have a code reader that will fit this car, but would it show codes even if the light isn't on? Thanks!

 

do not reset the check engine light. go to a mechanic. it might be 02 sensor and also tune up your own car.
it's easy.

 

Take it to Aamco they'll scan it for free, then post the dtc.

 

Thanks guys. What I am saying though is that my CEL is NOT on and I have not reset it. I am wondering if It will still show DTC's even though the light isn't on?

 

sorry i misread your posting

NOPE the CEL should be on. it will also pass emission test if the CEL is not on.
do you know how to tune up?

just tune it up. it might work?