Need Assistance? Live Chat
Need Assistance? (Se Habla Espanol) Call 1-877-702-1308 or Chat Online

Select by Category

Select by Brand

Get Email Exclusives

Sign up for email updates on the latest exclusive offers

Audi A4 Oxygen Sensor

The Usual Signs of a Malfunctioning Audi A4 Oxygen Sensor

Your Audi A4's oxygen sensor is an essential part of the car because it determines the correct fuel-to-air ratio for the engine. However, it only has a limited service life particularly for older models, and it could lead to different problems once it malfunctions. When you start to notice that your vehicle is acting unusual, you should do some troubleshooting immediately to determine if the problem is coming from a faulty oxygen sensor. Enumerated below are some of the common problems you can encounter:

Poor fuel mileage

When the oxygen sensor of your car begins to malfunction, your car will start to experience a decrease in fuel mileage. This happens when a faulty sensor determines the wrong amount of fuel-air mixture, and the amount of fuel that's sent to the engine's cylinders increases. Although there are other causes of poor gas mileage, you should include the oxygen sensor in the list of parts to check. When the oxygen sensor gets fixed, the fuel consumption of your vehicle can improve by as much as 40 percent.

Rough idling and stalling

Since the oxygen sensor in your car contributes to various engine functions like engine timing and engine combustion intervals, a defective oxygen sensor can be the cause of rough engine idling. The sensor in your car can become clogged because of contaminants like lead or carbon that comes from the engine. Air leaking in the exhaust manifold can also affect the performance of the sensor. You can try to clean or repair the sensor and the exhaust manifold when this happens, but replacing these parts is the best solution.

Increased vehicle emission

Another common problem you will notice when your Audi A4 oxygen sensor begins to malfunction is the increase in smoke emission. A bad oxygen sensor won't be able to measure the correct fuel-to-air ratio, and it will only cause unnecessary amounts of fuel to be sent to the engine. The unburned fuel will later accumulate and become toxic gases. A good preventive maintenance for an oxygen sensor is replacing it every 100,000 miles. This will help your vehicle meet the emissions test requirements.

Audi A4 Oxygen Sensor Bestsellers View more

  • Audi A4 Oxygen Sensor: Three Effective Ways to Keep It in Top Condition 27 February 2013

    The service life of your Audi A4's oxygen sensor can reach up to 100,000 miles. However, since the oxygen sensor of your car is located in the exhaust system, it is prone to carbon deposits and other sediments which may damage the sensor and shorten its use. To achieve the maximum lifespan of the oxygen sensor and to ensure that it works properly, here are a few maintenance tips you can follow:


    Clean the oxygen sensor.


    If your car's oxygen sensor is showing signs of wearing down, and you want to replace it with a new one but your budget is still short, then you can try cleaning it. To do this, you need to remove the oxygen sensor from the vehicle and place it in a container filled with gasoline. The amount of gasoline should be just enough to submerge the entire sensor. By gently rotating the container, the gasoline inside will swirl and wash through the sensor. You should leave the oxygen sensor overnight and dry it the next day.


    Test the oxygen sensor's voltage.


    With the help of a multimeter, you can determine if your car's oxygen sensor is working properly or needs to be replaced. But before you begin, you have to know the sensor's operating voltages for your Audi A4. You can refer to the vehicle service manual or call your local dealer to know that information. When you have already determined the operating voltages of the oxygen sensor, you may prepare your vehicle and start the sensor test. Remember that the rich fuel condition is close to 0.8 volts, so when the oxygen sensor fails to reach that output voltage, then it already needs to be replaced.


    Replace the oxygen sensor when it is already faulty.


    When you begin to notice symptoms from your vehicle like decreased fuel economy, faulty catalytic converter, and constant check engine light, then it's the right time to check the oxygen sensor. When you have finished checking the sensor and determined that it's the cause of the problem, there's no greater preventive maintenance than to replace it with a new one. If you let the faulty sensor last longer, you will risk other exhaust and engine system parts which could lead to even more expenses.