An oxygen sensor or most commonly known as the O2 sensor is a critical component of your car’s exhaust system. It measures the amount of oxygen in the exhaust to ensure an efficient air and fuel mixture. Once it wears out and throws error codes, or illuminates the check engine light, you should consider replacing it.
The average cost for oxygen sensor replacement is between $85 and $475 (labor and parts). If you think this is pricey, you may be asking “Can you drive with a bad O2 sensor?” or “Can I replace the O2 sensor myself”? We will answer those questions in this article.
- 1. How does a car oxygen sensor work?
- 2. Can you drive with a bad o2 sensor?
- 3. How far can you drive with a bad O2 sensor?
- 4. Can a bad O2 sensor cause engine damage?
- 5. How much does it cost to fix O2 sensors?
- 6. How to tell which oxygen sensor needs to be replaced
- 7. What are the symptoms of a bad O2 sensor?
- 8. What can cause an O2 sensor to fail?
1. How does a car oxygen sensor work?
Car sensors control everything in the engine for optimal performance. First, let’s take a closer look at how oxygen (O2) sensors work. The O2 sensor reads the exhaust in real-time to determine the air-fuel ratio. It then sends the data to the computer, and the computer adjusts the mixture accordingly by controlling the fuel injectors. Thus, O2 sensors directly impact how much fuel your vehicle’s engine burns.
Watch the video below to fully understand how O2 sensors work:
If the oxygen sensor fails, the computer won’t be able to set the correct air-fuel ratio. Consequently, if there isn’t enough air coming into your engine, you’ll have a lean mixture; if there’s too much fuel, you’ll have a rich mixture. In either case, oxygen content must be adjusted so that it matches what’s required for your engine to run properly.
Thus, a faulty O2 sensor may result in poor fuel economy, and sluggish engine performance, and worst, it may overheat the catalytic converter. As shown in the video, both O2 sensors are linked to the catalytic converter.
There are two types of O2 sensors, the upstream and the downstream O2 sensor. The upstream O2 sensor is installed before the catalytic converter whereas the downstream O2 sensor is located after the catalytic converter.
2. Can you drive with a bad o2 sensor?
Yes, you can still drive a car with a bad O2 sensor. However, it could be costly because it greatly impacts fuel consumption. Moreover, it could damage the catalytic converter, which costs around $900 to $2500 including parts and labor. Finally, it is also illegal to drive without functioning and unaltered O2 sensors.
With that being said, you should only consider driving your car with a bad O2 sensor if you intend to bring it to your mechanic for diagnosis and replacement. Although you can ignore this issue for a while, you are putting other components of your car at risk, especially the catalytic converter, the longer you drive without a working O2 sensor.
As discussed previously, if the vehicle has a faulty O2 sensor, the computer won’t be able to set the correct air-fuel ratio. If the mix is off and becomes too rich, your catalytic converter can overheat as a result. Although catalytic converters can also overheat because of excessive amounts of unburned gas caused by a misfiring spark plug or a leaking exhaust valve.
Oxygen sensors are also critical to passing the emission test. O2 sensors keep your emissions in check and alert you when emissions are too excessive. According to a 2022 article, over 40% of Americans live in cities and states with poor air quality. Thus, driving a car with a bad O2 sensor may only worsen the environmental impacts of motor vehicles.
Since replacing the O2 sensor is only 10% of what you could spend if the catalytic converter breaks down due to overheating, it is highly recommended to replace them as soon as you can.
3. How far can you drive with a bad O2 sensor?
You can drive from a few hundred to a thousand miles with a bad O2 sensor. But you should expect a significant decrease in fuel mileage and poor engine performance such as rough idling, stalling, etc.
This can happen on any car but is more common in older cars, especially those with higher mileage. It is recommended to have it replaced as soon as possible to avoid serious damage such as catalytic converter failure.
4. Can a bad O2 sensor cause engine damage?
What happens if you don’t replace your O2 sensor? Can a bad O2 sensor cause engine damage? No, a bad O2 sensor will not cause engine damage. The O2 sensor is installed within the exhaust manifold and is not directly part of your car’s engine system. You can still drive from hundreds to a thousand miles with a faulty O2 sensor.
However, as discussed earlier, a bad oxygen sensor can interfere with engine performance and fuel consumption. This is because the main role of the O2 sensor is to monitor the air/fuel mixture that goes into your engine, and if there is too much or too little fuel, the computer will adjust accordingly.
5. How much does it cost to fix O2 sensors?
Now that we have discussed what happens to a car when the oxygen sensor is bad, let’s take a look at how much it cost. Unfortunately, once it wears out, there is no temporary fix for O2 sensors.
You need to drive to your trusted mechanic or buy and install on your own. Depending on how many O2 sensors you need (it is best to replace O2 sensors in pairs or both upstream and downstream) and your preferred brand, the price ranges from $25 to $400.
Some of the recognized oxygen sensor brands are Bosch and Denso. You may also find great deals for aftermarket O2 sensors on Amazon by clicking on the links below:
Labor costs are estimated between $60 and $75. In most vehicles, replacing an O2 sensor is a simple procedure that only requires basic tools. So you may consider replacing the faulty O2 sensors on your own by following the steps in the video below:
6. How to tell which oxygen sensor needs to be replaced
To determine which oxygen (O2) sensor needs to be replaced, you will be needing an OBD II scanner such as the INNOVA 6030P OBD2 Scanner. It is an affordable scanner that can assist you with most check engine light problems including bad O2 sensors. With INNOVA 6030P you can diagnose your car’s O2 sensors directly, you can also see key information about your vehicle in real-time to aid in diagnosis.
You can tell which O2 sensor is malfunctioning by looking up the code and seeing which bank, sensor, and cylinder it refers to. For example, code P1647 for the description “Bank 2, Sensor 1”. If the code reader says sensor 1, it is referring to the upstream while anytime the code reader says sensor 2, it is referring to the downstream.
7. What are the symptoms of a bad O2 sensor?
Since it is an important part of the car to perform efficiently, you may be wondering “what happens to a car when the oxygen sensor is bad?”. A bad O2 sensor will not shut off a car. Although it could stall or cause misfires. Here are some of the most common symptoms of a bad O2 sensor.
- Illuminated Check Engine Light
- Poor Fuel Economy
- Rough Idling and Engine Misfires
- Failing Emissions Test
- Black Smoke Emission
- Rotten Egg Smell
8. What can cause an O2 sensor to fail?
Oxygen sensors can fail in many ways:
- Internal contamination from oil or coolant – Oil or coolant leaking into the sensor will cause it to stop working properly. Most modern O2 sensors operate within a narrow range of temperature and pressure, so if they’re contaminated by oil or coolant, they’ll simply quit working. This is usually caused by a bad head gasket or cracked cylinder head.
- Excessive oil consumption – Excessive oil consumption can also cause O2 sensors to fail. If there’s too much oil in the combustion chamber, it could coat the platinum tip inside the sensor and render it useless.
- Wear and tear – Even if you don’t have any symptoms such as rough idle or poor fuel economy, it’s still important to get all critical maintenance done on time because eventually even a good O2 sensor will fail due to normal wear and tear. We recommend replacing your sensors every 60,000 to 90,000 miles.
In this article, we answered the question, “Can you drive with a bad o2 sensor?”. Although a car with a broken oxygen sensor is driveable, it will cause higher fuel consumption and inefficient engine performance. The worst thing that could happen is damaging the catalytic converter which is 10 times more expensive to replace.
O2 sensors also monitor the amount of pollution the vehicle dispels from the exhaust system, which is crucial during an emissions test. You may also get penalized for driving without an O2 sensor. Thus, we strongly recommend avoiding driving with a bad O2 sensor and having them replaced as soon as you can.