You really need to have the knowledge of automotive before being able to figure out the meaning of Pontiac diagnostic trouble codes. Before it becomes as simplest as nowadays, there were so many steps of development since circa the 80s. And now, when everything is all computerized, you better know and understand the meaning of each code to find out any problem with your Pontiac.
First of all, you need to buy a scanner code tool in order to find out what is wrong with your vehicle especially if you see the illumination on the Check Engine Light. The scanner does not have to be expensive because the cheapest on the market is sold around USD 17. Anyone can operate that easily.
Make sure you have connected the scanner to the 16-pin DLC installed right under the steering column. You might see a cover of the connector. Turn on the ignition and then follow the instruction of the scanner to access the DTC.
Purchasing a scanner tool might be an excellent investment because if you do not have the scanner then you need to bring it to the repair shop. Other than that, acknowledge yourself about automotive or at least about Pontiac diagnostic trouble codes