Perhaps millions of motorists are driving across the United States and Canada with a bright yellow light illuminated on their dashboard warning them to check their engine. What's the light mean? It could mean hundreds of different things, but thanks to code scanners that are free at many auto shops, you can find the code and understand the problem.

As I arrived home for the Labor Day weekend and I began striking up conversations with my family, my dad had told me his check engine light was on just a few days after leaving the local Mazda dealership in Grandville, Michigan. I suppose it was a good thing that I come from an auto background and own my own code scanner. A code scanner plugs into a vehicle's diagnosis port, called On Board Diagnosis (OBD). OBD2 is the current standard on vehicles after 1996. I plugged my scanned into the Mazda 6 to see what it'd come up with.

It's fairly rare to have a check engine light pop up after a dealer service visit, in this case an oil change. My dad told me he had reset the light already using the code reader, only to see the check engine light come back on with the same codes. That's clearly a red flag that requires additional attention. As I read the two codes, it clearly became obvious that this was likely an issue with the service he experienced from the Mazda dealer in Grandville, MI.

The codes came back P2187, Lean condition. I recognized that this was an air intake issue, likely because the sensor reading airflow was being circumvented. Googling the code also found results. Knowing that the issue was tied to perhaps a vacuum hose or intake, I inspected those parts an immediately found the cause: a rip in the air intake hose, likely caused by the dealership when they inspected the air filter during the oil change. A simple call to the dealer, and while they reluctantly accepted blame, they still seemed to refuse that this could have been their fault.

Not only should motorists check engine codes as soon as possible after getting them, but not put off fixing them. Many check engine light issues can impact fuel economy, and some sensor problems can pose significant issues to your vehicle.

If you have a check engine light on in your vehicle, many local shops or tool stores offer a free readout of your engine codes. Some stores that I've used this service: Autozone, Advance Auto Parts, NAPA, etc. Call around to local garages to see if someone will read your code for free, and then research the engine code to find out if others have had this code- odds are you aren't alone!