Signs of a Bad Oxygen Sensor

Signs of a Bad Oxygen Sensor

By Michael Ales

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Herndon, Virginia ? Nobody wants to see the Check Engine Light come on when they are driving. That dashboard icon can mean serious problems for your engine. But the truth is, while it might be an inconvenience, it is not always the end of the world if it does light up.

For instance, did you know that one of the most common causes of a Check Engine Light is actually a loose gas cap? Yep. It can be that simple. That problem is second only to a slightly-less-simple and number one cause of a Check Engine Light: a faulty Oxygen Sensor.

What is an Oxygen Sensor?

An Oxygen (O2) Sensor is a device inserted into the exhaust flow of a car, truck, or SUV to detect the amount of unburned oxygen in the exhaust emitted by the engine. During combustion, an engine burns a mixture of air and fuel inside the combustion chamber. When those are out of balance, excess amounts of unburned fuel (running ?rich?) or unburned oxygen (running ?lean?) are produced and exit by way of the exhaust system. To correct this, an average vehicle has anywhere from two to four O2 sensors placed near the exhaust manifold or on the exhaust pipe near the catalytic converter. Together, these sensors send data to the vehicle?s engine control computer to help it identify if the air/fuel mixture is too rich or too lean for proper combustion in the engine. With the data, the computer adjusts the mixture for optimum engine performance and fuel economy.

It is possible for O2 sensors to last more than 100k miles. It is also common for them to fail before that. Usually O2 sensor failure is due to a buildup of combustion byproducts on the sensor, often as a result of cheap fuel and neglect. Regular engine maintenance and using quality fuel may prolong the life of these components.

How do I know if my O2 sensor is bad?

Since a failed O2 sensor is the most common cause of a Check Engine Light, a good clue that a sensor has gone bad is when the light comes on. A reading with a diagnostic scan tool can show if a sensor has stopped functioning properly. The diagnostic trouble code (DTC) revealed by the scan may also (in many cases) point to the specific sensor that is bad.

Other signs can point to a bad O2 sensor too, even before a Check Engine Light shows up. For instance, decreased fuel economy, erratic engine performance, or a failed emission test are all potential indications of one or more failing O2 sensors.

Can I replace the sensor myself?

Removing an old O2 sensor and installing a new one is a simple task ? in theory. The truth is, even if you are able to successfully diagnose which sensor is bad (not such a simple task), and locate the sensor (usually underneath the vehicle), removal is easier said than done. More often than not an O2 sensor is stuck in place due to the constant heating and cooling of the exhaust system and corrosion. A special wrench is often required for removal which, even when done by an experienced technician, often results in breaking the old sensor or mounting bolts. Heating with a torch may be necessary to prevent breakage. Not to mention, the vehicle must be suspended in the air for access to most O2 sensors ? a dangerous proposition without proper training and equipment.

Statistically, there is a good chance that one or more of your car?s O2 sensors need to be replaced when the Check Engine Light comes on in your car. Of course, there are many problems that can lead to a Check Engine Light. So, make sure to have your vehicle properly diagnosed by a qualified technician any time the light appears.

Hogan & Sons Tire and Auto| Author: Mike Ales | Copyright March 2018

This article is intended only as a general guidance document and relying on its material is at your sole risk. By using this general guidance document, you agree to defend, indemnify and hold harmless Hogan & Sons Tire and Auto and its affiliates from and against any and all claims, damages, costs and expenses, including attorneys? fees, arising from or related to your use of this guidance document. To the extent fully permissible under applicable law, Hogan & Sons Tire and Auto makes no representations or warranties of any kind, express or implied, as to the information, content, or materials included in this document. This reservation of rights is intended to be only as broad and inclusive as is permitted by the laws of your State of residence.


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