The Ultimate Oxygen Sensors Buying Guide

1 What Is An Oxygen Sensor and What Does it Do?

Out of the many sensors present in a modern-day automobile, the oxygen sensor is one of the most essential sensors that checks the air-fuel ratio via exhaust emissions. In the exhaust system of the vehicle, the oxygen sensor feeds the data collected into the ECU (Electronic Control Unit) based on which it regulates the amount of air and fuel being sent into the engine for combustion. This keeps the engine from running too rich or lean (excess fuel or deficient fuel) which further helps in keeping the emissions within permissible limits. 

Based on the oxygen content in the exhaust gases, the sensor generates electrical signals. The ECU measures changes in voltage and interprets this data in the form of air-fuel ratio and then makes the necessary changes to the ratio, ensuring the best possible engine performance. The voltage usually ranges from 0.1V to 0.9V. The higher the voltage, the richer the air-fuel mixture prompting the ECU to lean out the mixture and vice versa. 

How Important is an O2 Sensor?

The oxygen sensor is a crucial component of your vehicle’s emission control system. It measures the amount of oxygen in the exhaust gasses and sends this information to the engine’s computer, which then adjusts the air/fuel ratio to optimize combustion and reduce emissions. A faulty oxygen sensor can cause a variety of problems, including reduced fuel economy, increased emissions, and poor engine performance. If you suspect that one of your oxygen sensors is faulty, it’s important to replace it as soon as possible to avoid further damage to your vehicle and to ensure that it’s running efficiently. 

Top Picks For Oxygen Sensor

2 What Are The Types Of Oxygen Sensors?

Based On Heating Circuit

Based on Location

1. Upstream / Pre Catalytic Converter Oxygen Sensor: 

The upstream oxygen sensor is situated before the catalytic converter in the exhaust system. The ECU primarily calculates the optimum air fuel ratio based on the amount of oxygen measured by the upstream sensor in terms of voltage. The higher the voltage, the richer is the air-fuel mixture and vice-versa. The number of upstream sensors could vary based on the number of cylinders and the cylinder configuration of your vehicle. 

2. Downstream / Post Catalytic Converter Oxygen Sensor: 

The downstream oxygen sensor is situated after the catalytic converter. This sensor serves the purpose of checking the catalytic converter efficiency. The difference in the data provided by the upstream and downstream sensors is used by the ECU to calculate the catalytic converter efficiency. 

Based on Bandwidth

1. Narrowband Oxygen Sensor

A narrowband oxygen sensor detects only if the mixture is either rich or lean based on the Stoichiometric air-fuel ratio (ratio of air-fuel where complete combustion takes place, 14.7:1). However, this type of sensor does not tell how far off is the actual ratio from the stoichiometric ratio.

2. Wideband Oxygen Sensor

A wideband oxygen sensor is capable of detecting a wider range of air-fuel ratios, approximately 10:1 to 20:1. This helps in determining how far is the air-fuel ratio away from the stoichiometric air-fuel ratio resulting in better calibration under all engine conditions. 

3 What Are The Things I Should Consider While Buying An Oxygen Sensor?

A. Compatibility

The first and obvious parameter that you have to check for is the compatibility of the sensor with your vehicle. An unfit oxygen sensor could potentially cause more damage to the engine than the actual worn-out sensor. Any company manufacturing oxygen sensors would provide you with the car company and models that it is compatible with. You have to ensure that the given details suit your vehicle. 

B. Construction Quality

The construction quality could be considered an indicator of the service life of the sensor. The materials used in the construction of the oxygen sensor are the major differentiators between a good one and a bad one. The materials should be able to withstand a fair share of abuse while giving the best performance for the longest time possible. Stainless steel is considered one of the most durable and rust-resistant. Along with that, the usage of high-quality plastics minimizes the risk of the sensors melting over time with long exposure to heat.  

C. Budget

While you have to be considerate about spending on an oxygen sensor, there is no need for you to shell out generous amounts of cash on it. A little bit of research would help you make a wise choice and save money. 

D. Brand

Good brands have a general tendency to make really good products as it is their reputation at stake. A company’s track record in manufacturing automotive components should give you enough information to decide if it’s a good brand to go ahead with. Do not compromise with a local unknown brand since it could put your vehicle in jeopardy. 

4 Which Top Brand’s Oxygen Sensor Should I Choose?

Bosch Oxygen Sensors

Started by Robert Bosch in 1886, this German company has pioneered in manufacturing the best automotive components. Bosch was the first-ever brand to produce oxygen sensors back in 1976 and needless to say one of the best-selling oxygen sensors to date.

Part Numbers: 15703, 15512, 15889, 15511, 15286, 15284, 15717, 16167, 17321, 15733 and more.

Features & Benefits:

• A double laser-welded stainless steel body protects against contamination
• Seared protection tube due to 100% functional quality test
• Pre-coated threads with anti-seize compound right out of the box
• True Direct-fit OE connectors and harness

For more, you can visit our Bosch Oxygen Sensors section. 

Denso Oxygen Sensors

Denso is a Japanese automotive equipment manufacturer based in Aichi, Japan. Established in 1949, most of its parts meet OE standards. The company produces a wide range of products including condensers, radiators, alternators, starters, spark plugs, and lambda sensors/oxygen sensors. 

Part Numbers: 234-4506, 234-4852, 234-9007, 234-4078, 234-4598, 234-4212, 234-4061, 234-4001, 234-4070, 234-4137 and more. 

Features & Benefits:

• Corrosion-resistant stainless steel construction
• PTFE filter blocks efficiency-robbing contaminants
• Refined zirconia element improves sensor response

For more, you can visit our Denso Oxygen Sensors section. 

NGK Oxygen Sensors

NGK is a Japanese brand leading in the production of automotive and technical ceramics products. The company also majorly operates in the United States for the production of spark plugs and oxygen sensors. NGK’s oxygen sensors have a good reputation in the market and continue to hold that. 

Part Numbers: 21066, 23159, 22500, 21546, 23162, 21514, 22524, 25186, 24456, 22012  and more. 

Features & Benefits:

• Dual-coated platinum element for increased longevity
• 3-stage element overcoat protects against contamination
• Fast light-off times decrease emissions and improve fuel economy
• Pure alumina ceramic filters exhaust gas

For more, you can visit our NGK Oxygen Sensors section.

Delphi Oxygen Sensors

Headquartered in London, UK, Delphi is a leading aftermarket automotive parts manufacturer with technical centers, manufacturing sites, and customer services in 24 countries. The company is pioneer in the manufacturing of combustion systems, and electrification products in passenger and commercial vehicles. 

Part Numbers: ES20014, ES20000, ES20407, ES10882, ES20013, ES10923, ES10596, ES20005, ES20409, ES10923 and more.

Features & Benefits:

• Planar technology helps reduce emissions
• Features OE connectors and wire lengths within three inches of OE specifications, which results in easier installation and resistance to high temperatures, vibration damage, and wire corrosion, which protects signal accuracy and longevity.
• Industry’s fastest light-off times to reduce cold-start emissions and improved fuel economy over the aging sensor
• Unique sensor coatings protect elements from premature failure and are validated for lifetime operation with E85 and other alcohol-based fuels.
• Installation instructions are included and feature correct installation torque.
• OE tested to 150,000 miles, plus 2,000 hours of severe thermal testing

For more, you can visit our Delphi Oxygen Sensors section.

Richporter Technology Oxygen Sensors

Established in 2001, Richporter Technologies is a Canadian company that leads in the aftermarket automotive parts industry.  The company manufactures engine management and ignition products offering a full line of oxygen sensors, mass air flow sensors (MAFS), coils, distributors, synchronizers and cam and crank sensors, and many more. 

Part Numbers: OS5038, OS5092, OS5047, OS5016, OS5037, OS5044, OS5218, OS5045, OS5108, OS5026, and more. 

Features & Benefits:

• High-quality Japanese ceramic sensing elements
• Waterproof connector to perfectly match the vehicle’s mating harness
• Anti-seize thread coating pre-applied on all parts
• All accessories included for installation (rubber grommets, tie wraps, push-in clips)
• Protective cap on all models to protect the sensing element from dirt and contamination

For more, you can visit our Richporter Technology Oxygen Sensors section.

5 What Are The Symptoms Of A Bad Oxygen Sensor?

Like any other component, even the oxygen sensor could fail after a certain time. The variance in voltage could become lethargic, failing the ECU to perform necessary adjustments to the air-fuel ratio affecting the performance of the engine and could also trigger the check engine light. Here are some other symptoms indicating a bad oxygen sensor:

Bad Fuel Economy

Rough Idling And Misfires

Rotten Egg Smell

How to Tell Which Oxygen Sensor Needs to be Replaced?

If you suspect that one of your oxygen sensors is faulty, there are a few ways to determine which one needs to be replaced. Most V6 and V8 engines built after 1996 include at least two upstream O2 sensors and one or two downstream O2 sensors. Some engines can have up to six O2 sensors. An O2 sensor error code will show the sensor location by sensor number (1, 2, 3, or 4) and cylinder bank (1 or 2). You can usually find Sensor No. 1 in the exhaust manifold, while Sensor No. 2 is often located downstream of the converter. Cylinder bank 1 can be found on the same side as the engine’s firing order’s number one cylinder and it follows that Bank 2 is on the other side.

If you’re still unsure which sensor needs to be replaced, you can use a few tools to help you determine the faulty sensor. Depending on your oxygen sensor type, you may need one or more of these following tools: OBD2 Code Reader, Digital multimeter (DMM), and automotive diagnostic scanner with live data capabilities.

What Causes O2 Sensors to go Bad?

There are several reasons why an oxygen sensor might fail. Here are some of the most common causes:

1. Time: The lifespan of an oxygen sensor is typically between 3 to 5 years or 60,000 to 90,000 miles. Over time, the sensor can wear out and become less responsive, leading to failure.
2. Contamination: Oxygen sensors can become contaminated with byproducts of fuel such as lead, sulfur, and fuel additives. This contamination can cause the sensor to fail and send incorrect signals to the engine control unit (ECU).
3. High temperatures: High exhaust gas temperatures can cause oxygen sensors to fail prematurely.
4. Lack of maintenance: Regular maintenance can help prevent oxygen sensor failure. Neglecting your vehicle’s maintenance can cause the sensor to fail and lead to other problems.

6 What Can Happen If A Faulty O2 Sensor Is Not Replaced?

The ability of the Oxygen sensors to monitor the mixtures flowing out through the exhaust depreciates with age. This translates to the sensor giving out incorrect signals resulting in improper delivery of air and fuel to the engine. 

The most noticeable difference that you would find with a faulty sensor is fuel efficiency. While this could be one of the most common effects of the faulty sensor, on the other end, you could also observe a loss in power due to the improper air-fuel ratios.

The vehicle system runs into a mode known as the open-loop when the sensor is failing. This means that the system ignores any instruction that was incorporated in view of controlling the emissions thrown out by the vehicle. Therefore, the vehicle would fail the state emission norms test and would be deemed unfit to be driven on the roads.

While most owners do not realize there’s a sensor known as the oxygen sensor, it is one of the major sensors to keep the vehicle running. As the vehicle emissions system evolves to be better day by day, the role of the oxygen sensor amplifies and its health of it becomes equally important.

7 What Is The Cost Of An O2 Sensor?

A. Under $50

This is the price range where you would find the most commonly used oxygen sensors and they work well with most of the cars they are fitted to. Having said that, they do not bring as much reliability as their more expensive counterparts averaging a service life of 20,000 – 40,000 miles.

B. Over $50

Most of the sensors in this price segment are designed for durability and accuracy. It is the materials like metal and high-quality plastics involved in making these sensors that push the price into the higher segment. But it is worth noting that the higher price does not necessarily mean the best sensors. You have to do a fair bit of research before spending on such influential parts.

8 What Are The Features Of A Good Oxygen Sensor?

A. Longer Service Life

The longer the service life of the sensor, the better the engine runs for a longer period of time. Otherwise, you would find yourself replacing the oxygen sensor frequently and also paying a lot for the damages the bad sensor could have caused. 

B. Easy Installation

A solo user should be able to slot the sensor in place. This helps you dodge the extra installation fees that the service centers might add to your bill otherwise. A sensor with a screw-on design or plug and use adapter would offer quick and a tight fit in the exhaust system, 

C. Accuracy

It is based on the values fed by this sensor, the ECU manages the air and fuel entering the engine for combustion. Hence, the accuracy of the sensors holds a major ground in determining the best performance output from your engine. 

Bosch Oxygen Sensors – Part Number Catalog

Sub Category	Part Numbers
Bosch Oxygen Sensors	15703, 15512, 15889, 15511, 15286, 15284, 15717, 16167, 17321, 15733

Denso Oxygen Sensors – Part Number Catalog

Sub Category	Part Numbers
Bosch Oxygen Sensors	234-4506, 234-4852, 234-9007, 234-4078, 234-4598, 234-4212, 234-4061, 234-4001, 234-4070, 234-4137

NGK Oxygen Sensors – Part Number Catalog

Sub Category	Part Numbers
NGK Oxygen Sensors	21066, 23159, 22500, 21546, 23162, 21514, 22524, 25186, 24456, 22012

Delphi Oxygen Sensors – Part Number Catalog

Sub Category	Part Numbers
Delphi Oxygen Sensors	ES20014, ES20000, ES20407, ES10882, ES20013, ES10923, ES10596, ES20005, ES20409, ES10923

Richporter Technology Oxygen Sensors – Part Number Catalog

Sub Category	Part Numbers
Richporter Technology Oxygen Sensors	OS5038, OS5092, OS5047, OS5016, OS5037, OS5044, OS5218, OS5045, OS5108, OS5026

9 What O2 Sensor do I Need?

The type of oxygen sensor you need depends on the make and model of your vehicle. According to AutoZone, if your Check Engine Light is illuminated, it could be a sign of a faulty oxygen sensor. Here are some steps you can take to determine which oxygen sensor you need:

1. Check your vehicle’s manual: Your vehicle’s manual should have information on the type of oxygen sensor you need.
2. Use an OBD2 code reader: An OBD2 code reader can help you determine which oxygen sensor is faulty by reading the error code.
3. Use a digital multimeter (DMM): A DMM can help you test the voltage output of each oxygen sensor to determine which one is faulty.
4. Use an automotive diagnostic scanner with live data capabilities: This tool can help you monitor the oxygen sensor’s voltage output in real-time to determine which one is faulty.