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How Many Oxygen Sensors Does a Toyota Highlander Have?


Oxygen sensors are oxygen analyzers that are used in hospitals and fire prevention systems. They are used in cars to monitor the level of oxygen in the burning fuel. So how many oxygen sensors does a Toyota Highlander have?

There are at least two oxygen sensors in a Toyota Highlander. Newer versions can have up to four. The job of the oxygen is to monitor the amount of oxygen in the burning fuel.

This article sheds more light on oxygen sensors in Toyota Highlander, their location, and the replacement process.

What Is An Oxygen Sensor On A Toyota Highlander?

The oxygen sensor is a device in the car’s exhaust system located before and after the catalytic converter. The job of the oxygen sensors is to constantly monitor the oxygen level in the gas that exits the engine.

Types Of Oxygen Sensor

There are two oxygen sensors which are the upstream and downstream oxygen sensors. The upstream oxygen sensor is right before the catalytic converter while the downstream oxygen sensor is located after the catalytic converter.

Oxygen Sensor

The upstream sensor monitors and collects information on the number of pollutants in the engine. This information is then sent to the Engine Control Unit which will adjust the air-fuel ratio.

What Is The Size Of An Oxygen Sensor?

Oxygen sensors come in different forms ranging from socket to claw type. However, the standard size for an oxygen sensor is 22mm which is about 7 to 8 inches.

Some oxygen sensors have a heavy-duty capacity suitable for use on rusted or baked-on sensors.

How Long Do Toyota Highlander Oxygen Sensors Last?

The oxygen sensor of an older Toyota Highlander model can last between 30,000 to 50,000 miles which is between 3 to 5 years.

The oxygen sensors in newer models have additional heating sensors that allow them to last up to 100,000 miles which is between 7 to 10 years.

Can You Still Drive A Toyota Highlander With A Faulty Oxygen Sensor?

It’s possible to drive a car with a faulty oxygen sensor. Even with a faulty oxygen sensor, the engine can still start and you might not experience any driving difficulty.

However, if you notice you have a faulty oxygen sensor, it’s better you fix it at once. Driving with a faulty oxygen sensor is not safe and it can also affect the functionality of other parts of the car.

What Is The Result Of Failing To Change A Faulty Oxygen Sensor?

Failure to change faulty oxygen sensors will make the engine incapable of correctly setting the air-fuel ratio. This will increase your car’s fuel consumption and also result in higher emissions.

Additionally, it can cause damage to other parts of the car such as overheating the catalytic converter.

What Causes Oxygen Sensors To Fail In Toyota Highlanders?

Oxygen sensors are not built to last forever so they fail over time due to wear. However, an oxygen sensor might fail before its life span due to contamination.

Some of the things that can damage oxygen sensors include:

Silicates that remain in the exhaust system after the coolant burns in the engine due to a leaky head gasket.

Also, phosphorus from excessive oil consumption due to worn piston rings or valve seals can damage the oxygen sensor.

How To Check For A Bad Oxygen Sensor In Toyota Highlander?

When there’s an issue with the oxygen sensor, one way to spot the issue is through the check engine light on the dashboard.

You can run a diagnosis on your Toyota Highlander by connecting an OBD2 scanner to your car. If the scan produces an error code from P0130 to P0135 or from P0150 to P0155, it suggests that something is wrong with the oxygen sensor.

Another option is to perform a continuity check on the oxygen sensor with a multimeter to confirm if the heater circuit is broken.

Replacing A Faulty Oxygen Sensor In Toyota Highlander

Replacing a faulty oxygen sensor in your Toyota Highlander is something you can do yourself. All you require is a wrench and possibly a flashlight.

To replace a faulty oxygen sensor, you can follow these steps.

  • Firstly, you need to ensure the engine is cold before getting to work.
  • You might need to wear an overall because you are dealing with the exhaust pipe.
  • You need to locate the faulty sensor that needs replacement.
  • After that, you can unplug the connector from the oxygen sensor.
  • Use the wrench to unscrew the oxygen sensor.
  • Apply anti-seize lubricant to the threads of the new sensor.
  • You can use your hand to screw in the new oxygen sensor before tightening it with a wrench.
  • The last step is to connect the electrical plug of the new sensor to the connector.

Will A New Oxygen Sensor Improve Gas Mileage?

Replacing a faulty oxygen sensor can improve your Toyota Highlander’s gas mileage by up to 40%. If you notice that your Highlander is consuming more fuel, it might be due to a faulty oxygen sensor. More so if the car has up to 100,00 miles on Its engine.


Oxygen sensors play a role in ensuring the engine gets the right measurement of fuel to air ratio. A faulty oxygen sensor will affect the functionality of your car hence it’s better to replace it once you sense the problem.

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