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Mopar Upstream & Downstream O2 Sensors

Oxygen Sensors, what they are and why they’re important

You may be wondering how your OEM Mopar Oxygen sensors function and why you need them. Whether your just curious or whether you may need a new one, the answer is right here.

The purpose of An Upstream Oxygen sensor

  Oxygen sensors sense the exhaust gas in your car, telling the Powertrain Control Module (Engine Control Module) how rich or lean the fuel mixture is. By the oxygen sensor sensing if the fuel mixture is lean or rich, the Powertrain Control Module (Engine Control Module) can then determine the proper amount of fuel to add or remove in the cylinder to achieve a fuel mixture of 14.7:1. This is necessary for proper engine performance, fuel economy and emissions. If you are suffering from poor fuel economy, poor performance or a failed emissions test, your upstream oxygen sensor may be to blame.  

At we carry All currently available Dodge, Chrysler and Jeep Oxygen Sensors that work as your Original Part. Some vehicles have 2 and some can have as many as 4 Oxygen Sensors.  

All Mopar Oxygen Sensors are built and rigorously tested for performance, longevity and must meet the Dodge, Chrysler and Jeep specification standards.  

How can tell if your Upstream Oxygen Sensor is failing?  

There are a few ways to tell if your upstream oxygen sensor is failing. Bad heater performance is the most common, as an upstream oxygen sensor is very temperature sensitive. A good oxygen sensor shouldn’t get cooler than 570 degrees during operation. It’s also important to keep track of slow response rate. As a sensor begins to age and becomes lethargic it takes more time to react to the changes in the air/fuel mixture. This causes emissions to go up and fuel economy to go down. The final way is by reduced output voltage. The output range should be 2.5 to 5.0 volt, a malfunctioning upstream oxygen sensor will have problems changing threshold value. Many vehicle manufacturers recommend replacing Oxygen Sensors between 30K-90K miles to maintain proper fuel economy, performance and emissions.    

What About Downstream Mopar Oxygen Sensors?  

Downstream Oxygen sensors serve the same purpose, but it tells the computer something different. While the upstream oxygen sensor tells the computer the ratio of the exhaust, the downstream oxygen sensor measures the air/fuel ratio coming out of the catalytic converter, telling the powertrain control module the efficiency and performance of the catalytic converter. This assures proper emission control system perfomance. The Downstream Oxygen Sensor voltage for a “healthy” catalytic convertor is 0.45 volts.  

How to Tell if a Downstream Oxygen Sensor is Failing?  

The way to tell if a downstream oxygen sensor is going bad is very easy, if your check engine light is on with a stored or pending fault code for oxygen sensor performance your downstream oxygen sensor has failed.  

Conclusion: Oxygen Sensors are an integral part of your Dodge, Chrysler and Jeep Emissions systems and can majorly effect performance and fuel mileage. Trust for Factory Warranted Mopar Parts that keep your vehicle running perfectly.

Author: Ashley Cordova