How many O2 sensors does an Acura MDX have?

The Acura MDX, a popular luxury SUV, typically has four oxygen (O2) sensors. These sensors play a crucial role in monitoring the air-fuel mixture and emissions of the vehicle's engine, ensuring optimal performance and compliance with environmental regulations.

Oxygen Sensors in the Acura MDX

The Acura MDX, like many modern vehicles, is equipped with multiple oxygen sensors to provide comprehensive engine and emissions monitoring. These sensors are strategically placed throughout the exhaust system to measure the oxygen content in the exhaust gases, allowing the engine control unit (ECU) to make adjustments to the air-fuel ratio for efficient combustion and reduced emissions.

• The Acura MDX typically has four oxygen sensors:
  
  
  
  1. Two upstream O2 sensors, located before the catalytic converter
  
  
  2. Two downstream O2 sensors, located after the catalytic converter
  
  
  
  


• The upstream O2 sensors provide real-time feedback to the ECU, allowing it to adjust the fuel injection and ignition timing for optimal engine performance and fuel efficiency.


• The downstream O2 sensors monitor the efficiency of the catalytic converter, ensuring that it is effectively reducing harmful emissions before they are released into the atmosphere.

By having four oxygen sensors, the Acura MDX's engine management system can closely monitor and control the air-fuel mixture, resulting in improved fuel economy, reduced emissions, and better overall engine performance.

How much does it cost to replace the oxygen sensor on a Acura MDX?

The total cost to replace an Acura MDX O2 sensor typically ranges from $200 to $450, with the part costing between $50 and $200 and labor costing the rest. The final price depends on the specific sensor needed (upstream/downstream), whether you use OEM or aftermarket parts, and your mechanic's labor rates.
 
You can watch this video to learn how to replace an O2 sensor on an Acura MDX: 51sHighMiles GarageYouTube · Sep 4, 2025
Cost breakdown

• Part cost: Expect to pay anywhere from about $50 to over $200 for a single oxygen sensor, depending on the brand and if it's an OEM (Original Equipment Manufacturer) part. 
• Labor cost: Labor can add another $150 to $250 or more, depending on the mechanic's hourly rate and how long the job takes. A professional can often complete the job in 30 minutes to an hour per sensor. 

Factors that influence the cost

• Part type: Upstream sensors (before the catalytic converter) and downstream sensors (after the catalytic converter) have different costs. Location can also affect labor time. 
• Part brand: Using an official Acura part will be more expensive than a comparable aftermarket part from brands like Bosch, NTK, or Walker. 
• Labor rates: Shop labor rates vary by location and shop. A dealership will likely charge more than an independent mechanic. 

What is the most common problem with Acura MDX?

Common Problems:

• Transmission failure: Early MDX models had issues with automatic transmission failure, leading to costly replacements.
• Steering rack issues: Some vehicles experienced steering rack and pump failure, which led to a loss of power steering.

Should I replace all four O2 sensors at once?

No, you should not replace all four oxygen sensors at once unless a specific diagnostic indicates they are all failing. It's more cost-effective to replace only the sensors that have failed, as they do not wear out at the same rate. It is often recommended to replace them in pairs (e.g., both upstream or both downstream) if one fails, as the remaining sensor is likely in a similar condition and may fail soon, Reddit user. 
This video explains the importance of replacing O2 sensors in pairs: 57sMatt's ShopYouTube · Aug 9, 2017
When to replace all at once

• If your vehicle's computer reports all four sensors are failing simultaneously, as this may indicate a wiring issue rather than four individual sensor failures, Reddit user. 
• If the car has a history of issues that could foul all sensors, such as a prolonged engine running rich condition. 

When to replace in pairs

• If one sensor fails, replace it along with its counterpart on the same bank (e.g., both upstream or both downstream). 

When to replace just one

• If you only have a fault code for a single sensor, replace just that one and monitor the situation. 

You can watch this video to learn how to test O2 sensors: 44sEasyAutoFixYouTube · Sep 18, 2022
Other considerations

• Upstream vs. downstream: Upstream sensors are crucial for engine operation, while downstream sensors primarily monitor catalytic converter efficiency. 
• Preventative maintenance: Replacing sensors is not recommended as routine preventative maintenance because they do not all wear out at the same time. 
• Diagnosis is key: Always diagnose the specific sensor that is failing before replacing it, and if multiple sensors are failing, first investigate potential underlying issues that could have caused them to fail. 

How many O2 sensors does a 2016 Acura MDX have?

There are four oxygen sensors in the vehicle: two upstream sensors (one for each bank of cylinders) and two downstream sensors (one after each catalytic converter). The upstream sensors are positioned on the exhaust manifolds, while the downstream sensors are found on the exhaust pipes.