The Number One Cause of Your Blinking Check Engine Light

How a Faulty Oxygen Sensor Can Send You in for Service

It’s the most dreaded dashboard light, even worse than the low fuel light, and when it comes on, especially if it’s flashing, you and your car should be heading straight for the auto repair shop for a check engine light service. Your expert mechanic will have the right tools to read your car computer’s trouble codes and address the problem. But why does that light come on, and why is it such a big deal?

Your Check Engine Light (CEL) is a signal from your car’s engine computer that something is wrong. While a steady or blinking Malfunction Indicator Light (MIL-the more formal term) can mean a lot of different potential problems, the most likely cause is an issue with the oxygen (O2) or lambda sensor.

The O2 sensors (a typical vehicle on the road today has at least three) measure how much unburned oxygen there is in the exhaust as your engine processes gasoline. If there’s too much oxygen, a lean mixture is created, producing nitrogen-oxide pollutants that can damage your car’s engine and will certainly lead to a noticeable decrease in your vehicle’s performance. If there’s insufficient oxygen present, a rich mixture creates engine pollution, equally damaging to your car. Properly working lambda sensors ensure the right ratio (typically 14.7: 1) of oxygen to gasoline to optimize vehicle performance.

A functioning O2 sensor tells your engine computer how much fuel to expend. If the O2 sensors aren’t working correctly, your car’s engine has to guess how much fuel to use, guaranteeing you a poorly running car wasting fuel. However, a malfunctioning oxygen sensor can lead to costly repairs to your catalytic converter and/or spark plugs. In a worst case scenario, you might even need to replace them entirely. A faulty O2 sensor guarantees your vehicle won’t pass its emissions test.

So, that flashing check engine light is on, and you’re imagining your wallet emptying. Don’t panic, head to your trusted mechanic at a reputable shop like Smitty’s Maintenance Repair and Collision, who will run your vehicle through a specialized diagnostics system, decipher any fault codes, and get you the fix you need to get you back on the road.

If that check engine light is shining, call in or schedule a service appointment today to have your O2 sensors tested and a full check engine light service performed. After all, what’s more valuable than an optimally running car and your peace of mind?