A Faulty Oxygen Sensor Can Cause the Following Symptoms

November 1, 2021

Also called the O2 sensor, a malfunctioning oxygen sensor can wreak havoc underneath the hood. This sensor communicates with your automobile’s main computer chip to let it know how much oxygen is in the exhaust. If it sends the wrong information, the engine control module will make unnecessary adjustments to the fuel and air in the combustion chamber. Consequently, Pit Shop Auto Repair advises that your car, truck, or utility vehicle will experience one or more of the following symptoms.

Black Engine Exhaust

When your engine burns excess fuel, it creates black exhaust that flows out of the tailpipe. If the faulty O2 sensor sends information that causes the engine control module to unnecessarily increase the fuel in the combustion chamber, you will end up with black engine exhaust. You will continue to see this exhaust until you replace the dead oxygen sensor.

Engine Performance Issues

These fuel and air imbalances also cause engine performance issues. For example, if the combustion chamber is burning excess fuel, your engine will pick up and drop speed unexpectedly. If the combustion chamber has too much air in it, your vehicle’s acceleration and engine will sputter and hiccup. You will notice this particularly when you are driving faster.

High Emissions Levels

Unfortunately, excess fuel in the combustion chamber means excess hydrocarbons in your vehicle’s exhaust. As a consequence, your automobile will release high emissions levels in the exhaust that will cause it to fail any emissions test that it takes. In fact, a common reason why automobiles fail emissions tests is a faulty or malfunctioning O2 sensor.

Poor Fuel Economy

Naturally, if the imbalance in the combustion chamber is creating a problem with your engine’s efficiency, you will end up with a reduction in your vehicle’s fuel economy. Unfortunately, there is no way to avoid this if the O2 sensor is sending incorrect data regarding the oxygen levels in the exhaust. The engine control module is going by the numbers that it is receiving.

Rotten Egg Smell

Finally, aside from failing an emissions test, excess hydrocarbons in your vehicle’s exhaust can clog the catalytic converter. When this happens, you might smell rotten eggs, you will end up with excessive heat in the engine and underneath your vehicle, your engine performance will suffer, and, again, you may end up with black exhaust flowing out of the tailpipe.

Don’t worry. Pit Shop Auto Repair in Libertyville, IL, can help. Call us today to schedule an appointment for your automobile. We will test the oxygen sensor and replace it if necessary.

6 Warning Lights You Should Never Ignore in European Cars | Pit Shop Auto Repair
September 26, 2025
Pit Shop Auto Repair in Libertyville, IL, highlights six dashboard warning lights European car drivers should never ignore.
Transmission | Pit Shop Auto Repair - Libertyville
July 3, 2025
European cars are known for their performance, engineering, and smooth ride—but even the most finely tuned vehicle can run into problems, especially with one of its most critical systems: the transmission. At Pit Shop European, we specialize in servicing European makes and models, and we know that transmission issues can sneak up on you if...
Auto Repair | Pit Shop Auto Repair - Libertyville
July 3, 2025
When your check engine light comes on, your brakes start squeaking, or your car just doesn’t sound right, the last thing you want to deal with is an overpriced repair or pushy upsell. At Pit Shop Auto Repair in Libertyville, we believe car care should be straightforward, honest, and fairly priced—every single time. As your […]
Diesel Repair | Pit Shop Auto Repair - Libertyville
July 2, 2025
Top 5 Signs Your Diesel Engine Needs Immediate Attention Diesel engines are known for their power, durability, and longevity, but even the toughest trucks can break down if small problems go unchecked. Whether you’re hauling heavy loads or just depend on your diesel vehicle for day-to-day tasks, knowing the signs of engine trouble can save...
Diesel Truck | Pit Shop Auto Repair - Libertyville
June 4, 2025
How to Keep Your Diesel Truck Cool and Running Strong This Summer Summer is hard on vehicles—especially diesel trucks. Between the scorching heat, longer drives, and heavier loads, your engine works overtime. Without the right maintenance, it’s easy for problems like overheating, coolant leaks, or decreased performance to sneak up on you. At Pit Shop...
Vehicle on the road | Pit Shop Auto Repair - Libertyville
June 4, 2025
As temperatures rise, so do the demands on your vehicle. For owners of European luxury cars like BMW, Audi, and Mercedes-Benz, warm weather can bring out a unique set of maintenance concerns. While these vehicles are known for performance and engineering excellence, their precision systems can be more sensitive to heat-related stress than other makes....
A person is driving a car | Pit Shop Auto Repair - Libertyville
June 4, 2025
As the temperatures rise in Libertyville, so do the chances of vehicle issues if your car isn’t properly maintained. Summer heat, increased road travel, and unpredictable weather all take a toll on your vehicle. That’s why it’s important to run through a summer car maintenance checklist before hitting the road for vacations, commutes, or weekend […]
White car on the road | Pit Shop Auto Repair - Libertyville
May 7, 2025
As Illinois heads into the warmer months, many drivers start thinking about summer road trips, weekend adventures, and enjoying the open road. But rising temperatures can also mean added stress for your vehicle. Heat affects everything from your engine to your tires, which is why it’s important to give your car a little extra care […]
Car headlight | Pit Shop Auto Repair - Libertyville
May 7, 2025
Owning a European luxury vehicle isn’t just about driving—it’s about experiencing precision engineering, high performance, and exceptional comfort. Brands like BMW, Audi, Mercedes-Benz, and Porsche are built to last, but like any fine-tuned machine, they need proper care to stay at their best. At Pit Shop European, we specialize in servicing European vehicles and helping...
A/C Repair | Pit Shop Auto Repair - Libertyville
May 7, 2025
The Importance of Cooling System Checks in Diesel Engines Your diesel engine works hard—hauling heavy loads, powering work vehicles, and handling long drives in all kinds of weather. But as the temperatures rise, one system becomes more critical than ever: the cooling system. At Pit Shop Diesel Repair, we know how essential a well-maintained cooling...