Why is my check engine light on? Here are 5 common triggers

Novato Auto Service • December 22, 2023

It might be tempting to ignore the check engine light, but doing so could lead to potential break-downs and costly repairs. By promptly getting to the shop for diagnostics, you’ll have the best chance to identify and address the underlying issue before it escalates. At Novato Auto Service, we provide expert check engine light diagnostics and repair in the greater Novato, CA area. Here are five common causes of an illuminated check engine light.


Catalytic Converter Problems

The catalytic converter plays a crucial role in reducing harmful emissions by converting toxic gasses into less harmful substances. If the check engine light is on, it may indicate issues with the catalytic converter. A faulty catalytic converter can cause poor acceleration and a sulfurous smell.


Ignition System Issues

Problems within the ignition system—such as malfunctioning spark plugs, ignition coils, or the spark plug wires—can trigger the check engine light. A misfiring engine can lead to reduced fuel-efficiency and rough idling. Regular maintenance of the ignition system is crucial to prevent these issues.


Faulty Oxygen Sensor

One of the more common causes of an illuminated check engine light is a malfunctioning oxygen sensor. These sensors monitor the level of oxygen in the exhaust gasses and help regulate fuel injection. A faulty oxygen sensor can lead to decreased gas mileage and increased emissions.


Failing Mass Airflow Sensor

The mass airflow sensor (MAF) measures the amount of air entering the engine and ensures the proper air-fuel mixture for combustion. When the MAF sensor malfunctions, it can lead to rough idling and reduced engine performance. 


Loose or Damaged Gas Cap

A loose or damaged gas cap is a rather common trigger for the check engine light. The gas cap plays a crucial role in maintaining the pressure in the fuel system. If it's not properly sealed, it can lead to a loss of pressure, triggering the check engine light. 


Check Engine Light Repair in Novato, CA

For auto repair in Novato and the surrounding area, contact Novato Auto Service at 415-598-1488. Feel free to give us a call today to make an appointment!

By Novato Auto Service August 4, 2025
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By Novato Auto Service July 6, 2025
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By Novato Auto Service June 2, 2025
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By Novato Auto Service May 5, 2025
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By Novato Auto Service April 4, 2025
At Novato Auto Service, we’re proud members of the local small business community. It’s our mission to earn our customers’ total satisfaction by consistently providing expert auto repair, friendly service, and fair pricing. Whether you need an oil change or in-depth engine repair, our team of local mechanics will work diligently to get the job done right. And we’re appreciative when our customers offer feedback about the work that we did for them. Here’s a look at some of our recent customer reviews. “They solved a “check engine” problem, which turned out to be a faulty fuel sensor somewhere deep down the guts of my Jeep Renegade. Service was personable and transparent. Scott tested the car himself before and after the service. One week after I got the car back, Scott called me to check if everything was in order, which was very nice. The problem was solved and the car is running great. Thank you Novato Auto Service.” —Alex F. “Great service as always from Scott and his son!” —Jim M. “I never write reviews honestly, but THEY DESERVE MY COMMENTS!! The best service you could ask for. Scott and the crew certainly deserve the praise. I have been going to Novato Auto Service for over a half a decade and have zero complaints.” — Andrew B. “When it comes to regular maintenance service, Novato Auto Service is honest, trustworthy and reasonably priced. And Scott is a pleasure to deal with, excellent customer service and follow through every time. And I never feel taken advantage of, since I'm a female driver with just a basic knowledge about automotive mechanical issues. Thumbs up and 5 star review for Novato Auto Service. We will continue to bring our cars here for all our service needs.” — JCM “I have been using Novato Auto for over 15 years and always got great service and the work done right each time. Will be using their service for foreseeable future.” — Harry P. “Would give more stars if I could. Reliable service, kind staff and honest.” — Katie M. Auto Repair in Novato, CA When you need auto repair in Novato, CA and the surrounding area, contact Novato Auto Service at (415) 598-1488 . Feel free to give us a call to schedule an appointment!
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