Most vehicles today an on-board diagnostics computer (OBD) that continually tests the emission components and system operations of your vehicle.

A warning light generally indicates that the OBD has detected a malfunctioning fuel component, emissions component or a systems failure.

Isolated or one-time fault signals are eventually wiped from its memory, but persistent or serious faults are stored and eventually trigger a warning light.

So, how you should react to a warning light depends on how the light behaves:

Warning Light comes on then turns off

If the light comes on for a little while and then goes out, you may have a momentary problem in the system. Once the light goes out, the problem is no longer occurring but it may have caused the computer to store a diagnostic trouble code in its memory. This isn't cause for immediate action, however, you should take the vehicle in to your mechanic as soon as possible just to have it checked.

Warning Light stays on

If the light comes on and stays on, it indicates an ongoing problem. It may not be a major problem however it may affect your car's performance, gas mileage and emission levels. Definitely take your vehicle to a repair shop as soon as possible.

Flashing Warning Light

If the light flashes on and off, the vehicle has a severe problem that will cause additional damage. If your repair shop is nearby, take the car in immediately. If not, shut off the car and call your mechanic for assistance.

In short, if you have a light, you have a problem. A simple degraded oxygen sensor can increase fuel consumption by 10 to 15 percent. Definitely not what you want with fuel prices approaching $5.00 per gallon.

More serious problems, if left unrepaired, could cost you a considerable sum for procrastinating.

Automotive technicians use a scanner or scan tool to retrieve fault codes and diagnose these problems quickly and accurately.

Don't let a simple problem become one that is complex. See your mechanic as soon as possible.