Starting Problem

I have a 2002 Grand Prix GT, 3.8L. Sometimes (once or twice) I have noted that the car does not start properly. It is does not do this everyday...may be once a month. Can anyone help with the issue?
I called Firestone and the Dealer--they said that it would take $90 to check the system, and I do not want to give them money without any reason. If there is something...I will go get it fixed then.

How much does it usually cost to replace a starter ( in case that is bad)?

Thanks

Check the battery connections and cables. A common problem are the battery posts on the battery especially if still an AC Delco. You can get the complete charging system and battery tested for free at places like Autozone or Advance Auto. Also, make sure the starter solenoid and B+ (12 volts) cables on the starter are good and tight.

Thanks you! I will get that checked.

What are the symptoms of a bad starter?

Thanks you! I will get that checked.

What are the symptoms of a bad starter?

When you turn ignition to start no turnover (no starter engagement). Sometimes no noise at all or a clicking/chattering sound.

Or sometimes the starter will engage/whine but it does not engage with the flywheel.