The CarMD can be used for a variety of situation. You can determine why your Check Engine light is on. You might also want to check for not found problems before you have on a long road trip. Or maybe you live in a state where they do state emissions "smog" tests. You can use it to check your vehicle out before you take it to get tested. If you are looking for a used car to purchase you can use the CarMD to check it out for potential problems before you buy it. CarMD can be taken to the car dealership and a diagnostic test can be run quickly on the used car. Even if the vehicle has been tampered with, a vehicle's computer stores codes even if the Check Engine light wiring has been disconnected. CarMD will access these codes and display a red LED indicator if any are present. Also, if the seller has recently cleared the computer's memory, the CarMD tool will indicate a possible problem with a yellow LED indicator. You can be rest assured that you will be able to determine the vehicle's health before making a purchase.

　　On Board Diagnostics is a special program installed in your vehicle's computer system. It is part of the US government's mandate to help automotive manufactures lower their vehicle emissions. It is designed to check malfunctions, set a diagnostic code and turn on the Check Engine light when there is a problem. All 1996 or newer cars, light trucks, SUVs, and minivans manufactured or used in the US have the most advanced OBD, called the second-generation on-board diagnostics program.

　　Many vehicles that were manufactured in the 80s and early 90s use OBD1 technology. It is the predecessor to today's second-generation diagnostics program. Some vehicles made in 1994 and 1995 use OBD1 and others use OBD2 systems. CarMD will work on vehicles with an early OBD2 system; however there will not be any information in the database to tell you what might be wrong.

　　When your Check Engine light comes on it means that the vehicle's On-Board Diagnostics computer has found a problem that may affect emissions. This problem can range in severity from a loose gas cap, which wastes fuel and causes pollution, to an engine misfire, which may cause permanent damage. In any case, you really do not need to panic. Most of the time, this light is the vehicles' way of saying "get me checked out soon!"

　　Ten percent of all vehicles on the road today are driving with the Check Engine light on. However, you really shouldn't do that for long periods of time without checking it out. It could be something as simple as a loose gas cap or it could be something that is potentially dangerous and costly if you let it go.

　　The CarMD is a simple handheld device that will help you monitor your vehicle's health and will provide you with valuable information when something goes wrong. Even though you will probably still have to take it to a mechanic to get it fixed, you will have a good idea of what is wrong with your vehicle, what parts will be needed and how much it will cost. This is valuable information to have to make sure you are not being talked into repairs that are not necessary.