5 Symptoms of a Bad Oxygen Sensor in Your Car

Last Updated on May 11, 2019 by themechanic

The exhaust manifold contains a component inside of it called an oxygen sensor. In case you didn’t know, the exhaust gases from the engine’s cylinders are gathered by the exhaust manifold and placed into a single pipe. Meanwhile, the oxygen sensor detects the unburned oxygen levels of these exhaust gases. Sometimes the exhaust gases that come out of the engine have traces of unburned oxygen in them. This is important information for the engine control unit to receive from the sensor.

The engine control unit, which is the central computer of the vehicle, needs to know these oxygen levels in order to create a better balance of fuel and oxygen in the combustion chamber. For instance, if the engine control unit detects there is too much oxygen, then it will cause the intake valve to take in less oxygen for the engine. That way, there is a better balance of oxygen and fuel when they mix together in the chamber for combustion.

5 Bad Symptoms

If your oxygen sensor were to ever go bad or malfunction, it could disrupt the entire internal combustion process. The engine will not be able to perform its duties properly and the entire driving experience will be compromised. It is best to replace the bad oxygen sensor when you notice its troublesome symptoms. Otherwise, it could eventually lead to engine damage.

Below are the top 5 symptoms of a bad oxygen sensor in your car.

1) Bad Odor

If the inside of your vehicle ever smells like rotten eggs, then it could be coming from your exhaust system because of a bad oxygen sensor in there. Unless you want to keep breathing in these nasty fumes, you should take your vehicle to the mechanic and replace the oxygen sensor before the smell gets any worse.

2) Failed Emissions Test

If you live in a state which requires regular emissions testing of your vehicle, you may end up failing the test if your oxygen sensor is bad. This is due to excessive amounts of carbon emissions forming as a result of the bad oxygen sensor. Usually, half of all failed emissions tests are because of a bad oxygen sensor. You’ll need to get this problem solved fast if you want to comply with your local laws.

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3) Weak Engine Performance

When the oxygen sensor is bad, it does not give the engine control unit an accurate oxygen measurement. This, in turn, causes the computer to mismanage the flow of oxygen into the internal combustion chamber. If the engine gets the wrong amount of oxygen, its combustion with the fuel will not generate sufficient power to satisfy the demands that you place on it. As a result, the engine power will be weaker when you attempt to accelerate, causing you to not go faster.

4) Bad Fuel Economy

When the wrong amount of air goes into the engine because of a bad oxygen sensor, it may cause the engine to burn more fuel than normal. This will ruin your fuel economy because you’ll be going to the gas station more frequently to fill up your gas tank. Replace the oxygen sensor and it will restore your fuel economy again.

5) Engine Warning Light

One of the first symptoms of a bad oxygen sensor that you’ll experience is an engine warning light illuminating on the dashboard. Whenever there is an imbalance of fuel and air in the internal combustion chamber, the engine control unit is going to detect that something is wrong or unusual. Anytime this happens, it will activate the engine warning light to let you know that something strange is going on. You won’t know exactly what is wrong until you run a diagnostic check on the system.

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