Thank you all for your answers; they have been a lot of help and i shall go to Auto Zone (since they check it for free)
After 1994 on-board diagnostic 2 systems are installed in cars. Check engine light turns on when there is something wrong that may cause emissions to rise. A misfiring engine will cause the check engine light to flash. Misfire is serious because unburned gasoline can cause the cat converters to fail and is a bad pollution spewing out the exhaust. Who ever checks for free will want to sell you something: please ask if you can write down the freeze data too. With that information and how many miles on Your truck. Also before driving make sure the basics are done fluid levels engine trans coolant? Get back to answers and I will guide you best I know how. (Year my guess would be a camshaft position sensor issue) or a (Left rear bank 2 #2 O2 sensor)
If the car runs fine and the light drives you crazy cover it with black electrical tape. Other wise some cars have a reset button for the check engine light.
The check engine light comes on for a reason, the 2003 is OBD II compliant and means that there is something wrong with the Emission system, there is another check engine light that you need to be concerned with and that's the one for over heating and low oil pressure warning light. Since you did not elaborate I wanted you to make sure you have checked the oil in the car and the coolant level in the Radiator is ok, a few other things to check is are there belts missing? is the gas cap tight? once you find this out then go and have the codes read then you would have to post the codes in order to know what may be wrong. Some cars used to have lights that a mechanic had to rest after so many miles, and that was to make sure the customer brought the car in to check it for possible problems, and did not mean anything but that. But your Year is not set that way, Once you fix the problem you can clear the codes.
An uprated performance CPU chip is worthwhile it will give 10-15% increase in hp across the rev range.
