The Check Engine Light
The check engine light is a signal that the onboard diagnostics system has detected a malfunction in the vehicle's performance.
When the onboard diagnostics system finds a problem it cannot adjust, the computer turns on the check engine warning indicator and stores a trouble code in it's memory. These diagnostic trouble codes help identify the probable source of the problem, such as a malfunctioning sensor or a misfiring engine and can be read with a scan tool or diagnostic computer.
The light generally has two stages: steady (indicating a minor fault) and flashing (indicating a severe fault).
The check engine light will illuminate for a large number of reasons.
- The first step is to take the car to be scanned for codes, these diagnostic troubleshooting codes will indicate what has triggered the check engine light.
- With this information, you know if there is a problem that needs to be immediately addressed.
- It may be as simple as a oxygen sensor needing to be replaced, or may be something more serious.
- Pay attention to how the car is running. If the engine sounds different, the problem may be serious and should be diagnosed soon.
- If your car is running like normal, you may have more time to fix the problem.
- Until the diagnostic troubleshooting codes are read, there is no way of knowing for sure.
5 common reasons your Check Engine Light may go on.
1. Faulty Oxygen Sensor / O2 sensor.
The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen). When functioning, the O2 sensor sends data to the management computer located within the engine. In your car, a functioning O2 sensor ensures that your engine is running at top performance. Additionally, this sensor keeps your emissions in check and alerts you to when emissions are too excessive.
What will happen if I don't get the O2 sensor repaired?
Your engine will be less fuel-efficient as it will be burning more fuel than it needs, and a defective O2 sensor can also harm your spark plugs and exhaust system.
2. Damaged Exhaust System / Catalytic Converter.
A catalytic converter is a car component that works to reduce vehicle emissions and pollution. It is a metal canister installed in the exhaust system. It is filled with a chemical catalyst, usually a platinum and palladium mixture, and helps to convert the vehicle’s emissions into non-harmful gasses.
What if I don't get my exhaust system repaired?
Your vehicle may experience one or all of the following below
- Reduced Engine Performance
One of the first symptoms commonly associated with a bad or failing catalytic converter is a reduction in engine performance. The catalytic converter is built into the vehicle’s exhaust system, and as a result, can affect the performance of the engine if it develops any problems. A clogged converter will restrict exhaust flow, while a cracked one will leak harmful gas. Either fault can negatively affect engine performance and cause a reduction in power and acceleration as well as fuel economy.
- Rattling Noise
Rattling noises from under the vehicle are another symptom of a bad or failing catalytic converter. If a catalytic converter becomes old or damaged internally from excessively rich fuel mixtures, the catalyst coated honeycomb meshes on the inside of the converter can collapse or break apart, causing a rattle. The rattle may be more obvious when starting the vehicle and will worsen over time.
- Sulfur Smell from Exhaust
During engine combustion, sulfur-containing gasoline becomes hydrogen sulfide. A properly working catalytic converter will convert hydrogen sulfide into odorless sulfur dioxide. When failing, you may notice a sulfuric, rotten egg-like smell coming from the exhaust. Unburnt fuel left in the exhaust by the bad catalytic converter produces the odour, and may even cause dark exhaust smoke.
3. Faulty Spark Plugs or Plug Wires.
Spark plugs are an integral part of your vehicle's motor as they provide the spark that ignites the air and fuel mixture within the cylinders. This continuous ignition is what keeps your car moving.
If spark plugs are not checked with regular services, cleaned or changed when necessary, they can cause problems with performance.
Signs you need to check or change your spark plugs?
- Engine has rough idle.
- Trouble starting your car
- Engine misfires or engine surges
- High fuel consumption
- Lack of acceleration
4. Faulty Mass Airflow Sensor.
With a bad sensor, the engine will not know the right amount fuel to add to air coming in, causing problems including poor gas mileage, lack of power and more.
All cars take outside air and pass it into the engine through the air filter. The mass airflow sensor measures the amount of air entering the engine.
For an engine to perform properly, it needs a specific amount of air-fuel mixture.
The car's computer reads the amount of air coming into the engine from the mass airflow sensor and then calculates the correct amount of fuel needed for proper engine performance.
If the sensor goes bad, the engine will not know the right amount of fuel to add, causing problems including poor gas mileage, lack of power and more.
If the air filter is dirty it is common for the mass airflow sensor to get dirty and lose the ability to read the amount of air coming in the engine.
Routinely changing your air filter can improve the lifespan of your mass airflow sensor
5. Check Your Fuel Cap.
When it's loose or cracked, fuel vapors leak out and can throw the whole fuel system off.
This causes a reduction in fuel mileage and increases emissions.
If your car isn't feeling jerky, or surging when the check engine light comes on, the first thing you need to check is the fuel cap.
Pull your car over, unscrew the cap and take a look to see if it has any cracks in it, if no cracks retighten the cap.
Continue driving and see if the check engine light turns off. While not threatening to your engine, it's good to take care of this right away to improve gas mileage.