Most of us understand that when a car’s Check Engine light (CEL) comes on, we know there’s a problem with the car. But what kind of problem could it be?

On the one hand, a CEL could indicate a costly problem, like a faulty catalytic converter. On the other hand, it could just be something trivial, like a defective gas cap, fingers crossed.

It’s not all bad, in fact, one good thing about a Check Engine light is that it can find little problems before they become big, expensive ones. So, the first thing to do is visit an auto repair expert to have them find the problem and have them turn off that glaring, orange dash light.


When it senses a problem or error, your car’s engine computer, or ECU, turns on the Check Engine light, also called the malfunction indicator lamp (MIL). That’s it. Before 1996, auto manufacturers each had their own engine diagnostic system to help monitor emissions. To add to the confusion, some of these early systems only triggered warning lights and didn’t give anyone an easy way to diagnose the situation. These lights were sometimes referred to as “idiot lights.”

All of this changed in 1996 when a new standard called ODB-II was implemented. This improved things because OBD-II made it easier to find and figure out a car’s diagnostic trouble codes (DTC) and made manufacturers setup an easy way to get this information via a plug called the onboard diagnostic (OBD) connector. That’s why most ODB connectors now are located on the driver’s side, usually below the steering wheel.

These warning lights can be orange, amber or yellow, the color just depends on who made your car. No matter what the color of the light is, if you have a flashing CEL, your likely dealing with a more serious problem. Driving a car with a flashing warning light could lead to further damage.

We find that some drivers confuse their Service Engine light for their Check Engine light. These two lights are different. A Service Engine Soon or Service Required light just means the car is due for routine maintenance like an oil change for instance. If one of your dash lights is on and you’re confused about what it means, just contact your mechanic.


Auto repair technicians use a professional scan tool to diagnose codes. Car owners sometimes use hand-held code readers to pull or read error codes and some units can even clear or turn off DTC codes. A code reader can help give you more information about your car’s situation and you don’t have to be a mechanic to use one.

Please be aware that hand-held code readers are only diagnostic tools and that clearing a code will not actually fix the problem. The light’s going to come on again and, or the situation could get worse.

Some common DTC codes are:

  • O2 sensor (part of the emissions system)
  • Loose or defective gas cap
  • Catalytic converter
  • Mass air flow sensor (monitors the fuel injection system)
  • Spark plug wires


Some car owners chose to ignore their CEL. Did you know that a car with a Check Engine light on won’t pass a state vehicle inspection? Texas care’s about that warning light because, if it’s on, there’s a good chance that the car is polluting the air excessively and drivers should care because, in this situation, they’re probably getting poor gas mileage and wasting money.

We’re always here to help, if you have a question or concern about your car, please call us or stop by one of First Tire & Automotive’s three convenient Fort Bend County locations today.

If you know someone who’s concerned about a dash light or, while riding in a friends car, you notice a small strip of black tape on their dash trying to cover up an orange warning light, don’t laugh, we’ve seen it happen, please share this information with them.