An oxygen sensor handles the air/fuel ratio in the engine. The sensor reads the exhaust gasses in real-time to determine the ratio. Finally, it can adjust by controlling the fuel injectors. This sensor is essential for the all-around work of the engine.
But is it harmful to drive a car with a bad oxygen sensor? It sure is. Cars with a bad sensor will have a higher fuel consumption. Another major sign of faulty sensors is black smoke from the exhaust system. Finally, a bad O2 sensor will cause weak engine performance.
Stay with us; you will learn to identify a faulty oxygen sensor. Also, you will learn how to replace it and how it impacts the car’s performance. Enjoy!
How to Tell Which Oxygen Sensor Needs to Be Replaced
Several symptoms can point out to a faulty oxygen sensor. Amongst them are failed emission tests, check engine light often lightening up, stalling engine, power loss, poor engine performance, and fuel economy. We will cover most of these signs below.
Illuminated Check-engine Light
A bad oxygen sensor can indirectly cause an illuminated check engine light (CEL). It is an indirect cause because a poorly working sensor can impact the failure of other engine systems. Those other systems can trigger an illuminated or flashing CEL.
If you want to check out what is causing your CEL to illuminate, you can plug a car computer into a diagnostic system. Errors that can be connected with an oxygen sensor are usually P0172, P0136, P0135, and P0131.
Rough Idle
Any symptoms attributed to bad combustion are a sign of a worn-out oxygen sensor. In this group, we can put rough and uneven engine work when idle, frequent misfiring, or power loss.
An important sign that your oxygen sensor is in trouble can be felt when starting a car. Stalling, power loss, engine hesitation, and overall uneven work is an invitations for a mechanic.
Misfiring Spark Plugs
If all cylinders are misfiring, that can mean that the engine is not getting proper air and fuel quantities to run. That can be a symptom of a bad oxygen sensor. In that case, the oxygen sensor will send the wrong information to the car’s computer. That will result in misfiring spark plugs.
Lack of Power
An O2 sensor in poor condition can cause combustion problems, leading to a poor air-fuel mixture. That will create a significant lack of power when starting the car. Weak engine performance may disappear during driving, but that doesn’t mean the problem is gone.
Leaving this problem unresolved will cause major problems during driving. Poor engine performance will escalate, and driving will be harder as time goes by.
Stalling
Stalling comes after the problems of misfiring and lack of power are left unchecked. Stalling happens when the engine cannot sustain itself and work properly with the remaining working pistons.
Poor Fuel Economy
One of the key symptoms of a bad O2 sensor is high fuel consumption. If you notice it, don’t overlook it because it can cause major problems to your engine and exhaust system. The O2 sensor overlooks the injection of fuel. A faulty sensor will lead to excess fuel levels in the engine.
Black Exhaust Fumes
Black smoke coming from the exhaust results from an unbalanced air-fuel mixture. O2 is responsible for keeping this balance, which is an important sign that the sensor must be checked.
Check Out How to Check and Replace an Oxygen Sensor (Air Fuel Ratio Sensor):
How to Replace an O2 Sensor
If you are into DIY actions and have some mechanic experience, you can try to replace the sensor. We will describe a simple seven-step process to help you achieve this.
Step 1: Attempt to Identify the Faulty Sensor
Use an OBD scanner to identify the faulty sensor. With this scanner, you can identify most of the problems that the car computer system is reporting. See what error codes it shows up, and check in the error database.
You can start once you know which sensor is responsible for the problem. Before attempting to remove the sensor, wait for the engine to cool down. Oxygen sensors are located along the exhaust system, which can be very hot.
Allow it at least half an hour to cool down before removing the sensor. If you are unsure that the engine is cool enough, use protective gloves to check.
Step 2: Use a Jack to Lift the Car
Lifting the car is recommended for a simpler and easier approach. Park the car on a flat surface and place wedges behind the wheels. That way, the car will stay in place. Find a jack point and place a jack. Now lift the car with the jack, and place a jack stand.
Every car has four oxygen sensors. The only way to reach the second sensor is to crawl under the car. Now when the car is secured in place, crawl under the car.
Step 3: Before You Begin, Disconnect the Oxygen Sensor Connector
Before proceeding with the removal, disconnect the connector. Find the cable that is connecting the sensor with an exhaust line. There is a plastic plug that needs to be inserted into the outlet.
At the end of the plug is a small tab. Push the tab down and pull the plug back. If you can’t push the tab down, use the flathead screwdriver.
Step 4: Take Out the Oxygen Sensor
Old sensors may be hard to remove so penetrating oil will help. Spray oil on the sensor where it connects to the exhaust line. Give the lubricant 10 minutes to do its magic before unscrewing the sensor. If the oil didn’t help, try it a few more times.
If the oil can’t loosen the sensor, use a heat gun. It doesn’t have flames, so it is safe to use. For safety issues, use protective gear.
To remove the sensor, you will need a ratchet wrench. The easiest way is to use a 3⁄8 ratchet; if you don’t have it, you can use a ratchet with an open end. Place the sensor where it plugs into the exhaust line. To loosen it, move the wrench counterclockwise.
Once it is loosened, unscrew it by hand. If you can’t loosen it, or unscrew it, don’t force it. Take it to the professional.
Step 5: Compare the Broken Sensor With the New One
You can compare the sensor to the one you bought when you have the sensor. If you didn’t buy it yet, now you can use the old one to know what to buy. There are a lot of sensors in the market, but try finding the ones the manufacturer used.
Cheaper options are available, but their quality and guarantee are below anything you would want.
Pro Tip: Find the sensor that the manufacturer recommends and guarantees. That way, you are installing the right part in your vehicle.
Step 6: Attach the New Sensor
The new oxygen sensor comes with a bag of bronze gel. That gel is used to lubricate the sensor. Use an old rag to distribute the gel on the sensor threads. Threads are located in the metal ring near the tip of the sensor.
Place the tip of the sensor into the hole on the top of the exhaust line. When you place the sensor, center it properly. Start rotating it by hand, and be sure that it goes smoothly. Once you tighten it enough, use a wrench with an open end to secure it.
Don’t overdo it with the screwing of the sensor. If you tighten it too much, you may be unable to remove it.
Plug the connector back into the car. The connector will produce a snap sound, so you will be sure that everything is in place. Secure the cables so they are not touching the engine or any other hot spot. They can damage the cable.
Step 7: Clear the computer codes
Sometimes, even after the replacement of the sensor, the engine light may still be on. Use the OBD code scanner to delete any remaining error codes.
Ways Of Replacing A Oxygen Sensor
We listed all the steps for the best way to replace an oxygen sensor. That is the safest and easiest way to do it. Be sure to use all the safety equipment and follow all the steps. If you are unsure how to proceed or have a hard time, call a professional.
What Does a Car Do When the Oxygen Sensor Is Bad
It all depends on how bad the shape of the sensor is. We already mentioned all the symptoms that point out a bad O2 sensor. The car will, at the start, have bad fuel combustion. That will lead to stalling, loss of power, check engine light will be illuminated, and the car will have poor gas mileage.
As time goes by, the symptoms will worsen. It will be harder to drive and control the car. There will not be enough power to drive safely.
Check Out the Symptoms of a Bad Oxygen Sensor:
FAQs
Is O2 Sensor Cleaning Worth It?
There is a practice that we regard as bad in attempting to clean the O2 sensor. Usually, it is done by wire brush or with aerosol cleaner. That way, the dirt deposits can be partially removed from the sensor. We strongly disagree with this mechanic self-help because it can cause more harm than good. The O2 sensor is too important to let it work badly.
Can You Ignore a Bad O2 Sensor?
After ignoring the problems with the O2 sensor, the main issue is major problems with the catalytic converter. If the early warning signs are overlooked, that can cause the breakdown of the converter.
Replacing an O2 sensor can cost a region a couple of hundred dollars. The bill can rise significantly if the problem goes to the catalytic converter. These parts can cost between $500 and $2000.
So, in shorts, you can’t and shouldn’t ignore a bad oxygen sensor.
How Much Does It Cost to Fix an O2 Sensor?
It all depends on the car model. The part can cost between $20 and $100, but then the mechanic’s price comes. A laborer’s hour costs between $50 and $150, and it takes around half an hour to change the oxygen sensors. Some models have hard-to-reach sensors that will take longer to replace.
How Do You Test an Oxygen Sensor?
Oxygen sensors can be tested with a digital voltmeter. But before that, test with an OBD code reader to see if some errors are attributed to the oxygen sensor. The oxygen sensor is in trouble if it shows errors like P0135, P0136, or P0131.
It is time to pull out the voltmeter if it doesn’t show any of those.
– Turn the engine off
– Set your multimeter to mV
– Connect the red lead from a voltmeter to the sensor signal wire
– Connect the black lead from a voltmeter to the good ground
– Turn on the car and let it work. The sensor will start measuring the oxygen along
the exhaust path
– For results to be good, the readings should vary between around 300mV and
800mV. If the results are steady around 450mV, the sensor is not reacting to
the fuel mixture. But if the results are around 550mV, the mixture has too much fuel.
The other way to use a multimeter test is by setting it to measure resistance (Ω). This way, you can check if the heater inside the sensor is working.
– Connect the red lead to the heater
– Safely ground the black lead
– The readings should be between 10Ω and 20Ω when the heater is cold.
Is an O2 Sensor a Big Deal?
Oxygen sensors are an important part of the fuel and emission system. They measure the air-to-fuel ratio and are responsible for emissions control. If the O2 sensor is not working properly, that can result in poor fuel combustion.
Bad fuel combustion can lead to several problems with driving and overall engine performance. The engine can stall, will not have enough power, and will be difficult to drive. Replacing the bad sensor with a new oxygen sensor will ensure efficient fuel combustion and correct engine timing.
Final Considerations
Driving with a faulty O2 sensor is not a joke. The car will have poor fuel economy and not pass an emission test. Driving it will be a nightmare because of all the stalling and loss of power. Do not waste any time and resolve this issue as soon as possible.
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