Check Engine Light on? 

Picture this-- you have a relatively new Toyota, running well with great performance and reliability- suddenly you are confronted by a “Check Engine” light on your dash. Many people get panicked by such a sight. Don't worry-- it could be a number of things, most of which are not major issues. Here are the five most common:


1. Your gas cap needs to be tightened, or it is damaged.

The first thing you want to check is your gas cap. Since it seals the fuel system and maintains fuel tank pressure, it prevents gas fumes from being released into the atmosphere when your vehicle is not in use. If a mechanic were to use a scan tool in this case, it would simply show what is called an “Evap code”. The check engine light alerts you to a loose, broken, or missing gas cap so you can tighten or replace it before you lose too much fuel through evaporation. It is not uncommon for people to have a “check engine” light come on right after they fueled up, and neglected to tighten the cap all the way.

2. You have a bad O2 Sensor and it Needs to Be Replaced

The 02 (aka Oxygen) Sensor measures the amount of unburned oxygen in your exhaust system. If the engine is not burning all of the O2 in the combustion process, it will trigger the code. It is more common to have a bad sensor than to actually have a combustion problem. In addition to causing your check engine light to turn on, a bad O2 sensor will have a negative impact on fuel economy, spark plugs or your catalytic converter.

3. You have a bad mass airflow sensor.

Like the 02 Sensor, the function of the mass airflow sensor is to measure the air, but in this case, the air that enters the engine, rather than the product after combustion. If the sensor is not functioning properly, it can cause damage to the spark plugs, oxygen sensors, or catalytic converter, and your vehicle will experience decreased performance and fuel economy.

4. You have a Bad Catalytic Converter

Your catalytic converter uses ceramic and particular metals (such as palladium) to converts noxious gases like carbon monoxide into carbon dioxide. Over the course of time, the interior surface can be compromised, and that will cause you to fail emissions tests, experience poor performance and economy as well as causing your car to run at higher temperatures.

5. You have either Bad Spark Plugs or Spark Plug Wires

This would be more common in older cars, . Spark plugs ignite the air-fuel mixture and power your engine while spark plug wires transfer that spark from the ignition coil to spark plugs. If the insulation on the wires is worn or cracked, it can cause some of the energy from the spark to arc, and the cars computer will see the voltage irregularity. Likewise a fouled spark plug can cause an incomplete burn during combustion.

Other than the source of the problem being the gas cap, none of the above solutions are a “Do-it-Yourself”scenario. Fortunately, Toyota of Braintree has numerous ASE Certified technicians who can quickly diagnose and solve your Check Engine light problem. To schedual service, call 781-848-9300, or schedule online HERE.