Mechanics say even a few small adjustments can shave hundreds of dollars off of car maintenance fees. NY1's Consumer Watch reporter Asa Aarons filed the following report.

The regular commuter car has something in common with the original Apollo 11 mission to the moon -- both mechanisms rely heavily on sophisticated computer systems. However, the modern car has more computer chips and processing power than the older moon module.

Most cars made after 1996 have a sophisticated diagnostic system that monitors and warns of potential problems. A gadget called CarMD plugs into the system and checks for errors and faults and sees what parts are running smooth.

The makers of CarMD people recently compiled data from nearly 200,000 checkups and they have found which parts work and which ones do not. This one-of-a-kind index is an opportunity to learn a great deal about the car and which parts need maintenance.

When the car's engine light goes on, the likely problem is a faulty oxygen sensor.

"That can lead to an immediate 40-percent reduction in fuel economy -- so something that costs consumers every day at the pump," says Art Jacobsen of CarMD.

Other common and costly problems discovered by the diagnostic survey are a loose or missing gas cap, a damaged catalytic converter, a malfunctioning mass air flow and then misfiring spark plugs.

The damaged catalytic converter is the most expensive common automotive malady, but it only comes about when smaller problems add up.

"A catalytic converter cost roughly $2,000 to replace, and what happens is when consumer neglect small problems like spark plugs or oxygen sensors, it leads to this part melting," says Jacobsen. "Take care of your vehicle, it's the second-largest investment that you're ever going to have in your life, for most people. It's something that you need to take care of and address small problems before they become large problems."

The good news is most of the common problems can be fixed cheaply -- and that is the subject of the next NY1 Consumer Watch report.