AAMCO Centers of Southern California


AAMCO Centers of Southern California

Check Engine Light On? Here's What to Do (And Not to Do)!

Learn the best course of action when you see this critical vehicle warning light illuminated on your dash.

AAMCO Socal  | 05/17/2022  | Auto Repair & Maintenance

Share  | 

Check Engine Light On? Here's What to Do (And Not to Do)!

It’s always distressing for any driver to see a Check Engine Light (CEL) staring bright-eyed at them on their dashboard. Ironically, a CEL is both very clear and very vague: it’s clear that you need your vehicle checked by a technician immediately; it’s vague because it can signify many issues, both small and big.

What Is the Check Engine Light (CEL)?

The “Check Engine” Light, or CEL, is also sometimes known as the “Malfunction Indicator Lamp” or MIL and is the most common signal from the computerized control center of your car that something is wrong within the engine. 

The CEL doesn’t offer any additional information on the exact nature of the problem. Its primary function is to warn the driver of an issue that cannot be corrected for and to have it properly diagnosed and remedied by a trained technician.

The Top Reasons for the CEL Illuminating

There are several common reasons why the CEL illuminates. Some reasons are more concerning than others. Please note that this list is not exhaustive, and there are many other possibilities.

Loose Gas Cap

If you’ve just topped up your gas tank and failed to put the gas cap back on properly, the CEL may flick on. If you see this right after the gas station, check to ensure your gas cap is on and tightened firmly.

Faulty Oxygen Sensor

This sensor checks on the air-fuel mix in your vehicle to help keep it at optimum levels. The engine can’t guarantee the best air-fuel mixture when this sensor malfunctions, so the CEL light will come on. This sensor is tied to the catalytic converter, so if it’s not giving the correct information to the catalytic converter, failure of that component could result.  

Catalytic Converter

We love our clean air in Southern California, don’t we? Thank your functioning catalytic converter, which breaks down harmful gases before they exit through the exhaust pipe. The CEL will warn you if something is wrong with the converter or any connected or independent part, such as the spark plugs (see below). 

Broken Mass Air Flow (MAF) Sensor

The MAF is essential for measuring how much air is getting into the engine. When it’s not working, the car’s computer can’t accurately determine how much fuel is required to run the engine properly. That’s when the CEL will illuminate.

Damage to the Spark Plugs or Wiring

Your spark plugs and various wires running in and around the engine are like joints and ligaments that help keep the system running properly. Many major components like the above-mentioned catalytic converter depend on these electrical components. That’s why you see the CEL whenever there’s a problem with them.

What to Do When You See Your CEL Light Come On

Do Not Ignore It

Because a vehicle may drive normally when the CEL illuminates, many drivers dismiss this important warning light, believing the system is just acting up or being too sensitive. This can result in problems worsening, causing system failures and expensive repairs. The best course of action should be to get your vehicle into an auto repair shop for an OBD-II scan to determine what’s wrong.

Flashing CEL: Don’t Even Drive

If you see a flashing CEL, it could indicate your engine is misfiring. These are no ordinary misfires, however. The flashing CEL indicates that unburned fuel is dropping into the exhaust system. This is very dangerous and can seriously damage your catalytic converter, which is among the most expensive components on your car to repair or replace—especially in California.

Therefore, if you see the flashing CEL when you start your vehicle, don’t drive. If you’re already on the road, find a place to pull over and immediately call roadside assistance.

Contact a Trained Auto Technician for Help

Once you see a CEL, your immediate goal should be to get your vehicle to a trained professional so that it can be scanned with an OBD-II diagnostic tool. The scan will produce a code indicating which component is experiencing the problem, allowing your technician to quickly isolate the problem and discuss solutions with you. 

Follow Your OEM-Recommended Maintenance Schedule

To help keep your CEL from illuminating, stick to the recommended maintenance schedule for oil and filter changes, belt and hose inspections, wheel alignment, and fuel system checks. The more you skip on regular maintenance, the more likely you’ll be greeted by a CEL.

Check Engine Light is On? Book Your Appointment Now

If you notice your CEL coming on—even if it just appears temporarily and disappears—the best thing to do is contact a Southern California AAMCO Center near you and schedule an appointment with one of our technicians today! Getting a diagnostic scan and determining the exact problem is the only way to fix whatever is causing that light. You’ll be glad you sorted it sooner rather than having expensive repair headaches later.

AAMCO has more than 50 years of experience diagnosing, servicing, and repairing more than 20 million vehicles. Customers rely on us for:

  • Quality repairs
  • Expert technicians
  • Superior customer experience
  • Trustworthy, honest service
  • Best warranty coverage available

AAMCO Centers of Southern California and surrounding areas represent trust, quality, and value. If you’re Check Engine Light is on, call us today!

Related articles

People watch the most on ...