Audi is a symbol of high-class, luxury, and performance. In order to maintain that quality, however, oxygen sensors (O2 sensors) must be working properly. Most cars have two oxygen sensors, and when they go bad, performance and fuel economy drop significantly. It’s important to understand how they work in order to see why they are so critical to ensuring your Audi runs and drives as it should.
O2 sensors are located in the exhaust system. Typically, one is placed near the exhaust manifold while the other is located close to the catalytic converters. This is the portion of the system that helps convert harmful emissions into less harmful substances.
Their job is to monitor oxygen levels in the exhaust gases; hence the name: O2 sensor. The readings are constantly sent from the O2 sensors to the Electronic Control Unit, or ECU. This is the onboard computer of your car’s engine. From there, the ECU uses this data to determine the proper air/fuel mixture for optimal performance.
If the O2 sensors go bad, the ECU won’t receive accurate readings about the oxygen content. Your Audi’s engine performance will suffer greatly. This occurs because your Audi demands a precise mixture of fuel mixed with air in order to complete the combustion process efficiently. Without the O2 sensor’s feedback, the ECU cannot accurately determine the ratio of air to fuel needed during each combustion cycle.
Luckily, there are some clear signs your O2 sensors are in need of replacement, so you can fix this issue as quickly as possible.
Signs of Audi O2 Sensor Failure
- Lowered fuel economy: The miles per gallon you average will drop drastically. You might notice you have to refuel much more than usual. Some vehicles come equipped with an option on the dashboard to check fuel economy, as well.
- Reduced performance: Your Audi will not drive like it used to. You might notice the engine hesitates, idles rough, or even stalls
- Black exhaust fumes: In addition to being alarming, black smoke from the exhaust is a signal the O2 sensors are no longer functioning properly.
- Failed emissions: If your Audi undergoes an emissions test and fails, the O2 sensors are a likely culprit. If this happens, your local DMV will not register your vehicle until the issue is resolved and passes emissions, making repairs mandatory.
- Fouled spark plugs: The spark plugs might be contaminated, although this can only be seen by visually inspecting the plugs.
- Check-engine light: Sometimes the check-engine light will illuminate on the dashboard, signaling something is wrong and in need of urgent attention. Any time this light comes on, it’s important to find out why. Local automotive service stations will have a device called an OBD-II reader that will read the codes on your Audi to find out which system has an issue.
Any of these signs can be caused by malfunctioning O2 sensors, which can be caused by contaminated fuel, the engine burning oil and leaving carbon deposits on the sensors themselves, dirt/debris from the road damaging the sensors, or simply that the sensor is old and is naturally failing. O2 sensors typically last a long time, however, and shouldn’t fail prior to 100,000 miles in most cases.
Given your Audi won’t be pleasant to drive if you’re experiencing any of these symptoms, or you might even be unable to register it to be driven on the road, it’s important to have the issue remedied by a qualified mechanic.
Bavarian Auto for Your Audi O2 Sensor Replacement
Since 1981, Bavarian Auto has been Chattanooga’s choice for import vehicle maintenance, service, and repairs. We also serve nearby areas of Ooltewah and Hixson, Tennessee, as well. As an independent, family-owned business, we treat our customers like family. We have over 120 years combined experience with imports, including Audis. The latest in equipment is used and an ASE certified master technician is sure to be able to diagnose your Audi and get you back on the road quickly and safely.