A loose or worn gas cap or a faulty catalytic converter are two common items which can cause Check Engine Light to illuminate.
Resources for the Repair and Maintenance of your Pontiac GTO
Pontiac GTO Models:
Pontiac GTO Problems
A coolant leak may develop from the water pump. This can result in an engine overheating condition. A leaking water pump will require replacement.
One or both secondary air injection check valves may become restricted causing poor air flow resulting in illumination of the Check Engine Light. It is often recommend to replace both check valves even if a fault code is set for only one bank of cylinders. Replacing only one valve may result in a return trip to the repair shop.
A dirty throttle body may cause a lower than normal idle and possible stalling condition. Performing a throttle body service will commonly correct this concern.
Pontiac GTO Questions and Answers
When I turn off car-radiator fan keeps running. I have replaced relay and still does it. Runs battery dead.
This is a general maintenance question
tie rods repair and costs
This only happens when the I drive the car, park it for 5mins jump back in and start it up. I have replaced the gas cap and its still pulling the codes