Why Is My Check Engine Light On? Causes and Troubleshooting


At All Valley Car Care, we understand the concern and uncertainty that arises when your check engine light comes on. As ASE-certified mechanics serving Gilbert, Phoenix, Surprise, and Scottsdale, AZ, we are here to help. With our advanced diagnostic tools and experienced technicians, we can pinpoint the issue and recommend the necessary repairs. In this blog post, we will explore the reasons why your check engine light may be on, provide insights into why it comes on and off, and offer troubleshooting tips to address common issues.

Understanding the Check Engine Light

The check engine light is a dashboard warning signal connected to your car’s onboard computer. It illuminates when there is a problem related to the engine or the combustion process. To identify the source of the issue, our ASE-master certified technicians will use a scan tool to retrieve fault codes. These codes guide us in accurately diagnosing the problem, whether it’s a loose gas cap or a clogged catalytic converter. At All Valley Car Care, we ensure that you have a clear understanding of the issue and obtain your approval before proceeding with any repairs.

Common Causes of a Check Engine Light

  1. Loose or Damaged Gas Cap: A loose or damaged gas cap can trigger the check engine light.

  2. Faulty Oxygen Sensor: A malfunctioning oxygen sensor may affect fuel efficiency and emissions.

  3. Malfunctioning Catalytic Converter: Issues with the catalytic converter can cause the check engine light to come on.

  4. Failing Mass Airflow Sensor: A faulty mass airflow sensor can disrupt the air-fuel mixture, leading to engine problems.

  5. Issues with Spark Plugs or Ignition Coils: Worn-out spark plugs or faulty ignition coils can affect engine performance.

  6. Problems with the Throttle Position Sensor: Malfunctioning throttle position sensors can result in poor acceleration or stalling.

  7. Faulty EGR Valve: A malfunctioning Exhaust Gas Recirculation (EGR) valve can trigger the check engine light.

  8. Issues with Fuel Injectors: Clogged or malfunctioning fuel injectors can affect fuel delivery and engine performance.

  9. Transmission-Related Problems: Transmission issues such as low fluid levels or solenoid problems can cause the check engine light to illuminate.

Troubleshooting Tips for Check Engine Light

  1. Checking the Gas Cap: Ensure the gas cap is tightly secured or replace it if damaged.

  2. Using an OBD-II Scanner: Use an OBD-II scanner to read the fault codes and gain insights into the issue.

  3. Addressing Minor Issues: Try restarting the engine and see if the light goes off. Sometimes, minor glitches can trigger the check engine light temporarily.

  4. Inspecting and Replacing Oxygen Sensors: Faulty oxygen sensors can be replaced to restore proper engine performance.

  5. Cleaning or Replacing the Mass Airflow Sensor: Clean or replace the mass airflow sensor to improve the air-fuel mixture.

  6. Checking Spark Plugs and Ignition Coils: Inspect and replace worn-out spark plugs or faulty ignition coils.

  7. Inspecting and Cleaning the Throttle Position Sensor: Clean or replace a faulty throttle position sensor to ensure smooth engine operation.

  8. Cleaning or Replacing the EGR Valve: Clean or replace a malfunctioning EGR valve to rectify emission-related issues.

  9. Addressing Fuel Injector Problems: Clean or replace clogged or malfunctioning fuel injectors to restore proper fuel delivery.

  10. Checking Transmission Fluid: Ensure proper transmission fluid levels and address any transmission-related problems.

When to Seek Professional Help?

If the check engine light persists despite troubleshooting or if you have limited knowledge and experience in car diagnostics, it’s advisable to seek professional help. Additionally, if safety concerns arise or you suspect major issues, it’s best to consult our ASE-certified mechanics at All Valley Car Care.

Reach Out To All Valley Car Care Today

Understanding the reasons why your check engine light is on and knowing how to troubleshoot common issues can save you time and money. At All Valley Car Care, we offer top-notch check engine light repairs, providing a 2-year/24,000-mile warranty on qualified repairs. Trust our family-owned and operated shop to handle your vehicle with care and professionalism. Visit us in Gilbert, Surprise, or Scottsdale, AZ, and let our experienced technicians resolve your check engine light concerns while you enjoy our comfortable waiting room or take advantage of our convenient shuttle service. Contact All Valley Car Care today at (623) 243-6206, (480) 497-4787, (623) 581-9554 & (480) 284-5488 for quality check engine light repairs and peace of mind.