Features:

• 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"  connectors and harness
• Base ceramic probe of Zirconium and Yttrium: Forms a tough base that resists cracking from mechanical and thermal shock

?

?Fitment:

2004 Subaru Legacy 2.5L
2004 Subaru Outback 2.5L

FAQ of oxygen sensor:

Question 1: Do I need to replace all of my oxygen sensors at once?

A: It is best to replace your sensors in pairs. For example, if you replace the downstream left sensor, you should also replace the downstream right. However, on most vehicles produced since 1996, replacing one sensor (especially the front engine monitoring sensor) will cause the ECU to set a code for the other sensors. 
This is because the new sensor switching activity is much faster than that of the older aged sensors. It is probable that on most vehicles, the code will be set within 30-60 days AFTER the first sensor replacement.

Question 2: How do I locate specified sensor locations (B1S1, downstream left, etc.)?

A: Left and right sensor positions are found in reference to the rear of the engine (the side opposite of the belts).
Upstream (pre-cat) and downstream (post-cat) are found in reference to the catalytic converter. 

Question 3: How to replace an oxygen sensor?

Step 1: Locate the oxygen sensor.

This sensor is usually located on your vehicle's exhaust pipe. If you see something attached to the pipe that looks like a spark plug, then you've found the sensor. You can also consult your car manual since the sensor's exact location depends on your vehicle's make and model.

Step 2: Disconnect the sensor's electrical wires.

Use screwdriver to pry the tabs that connect the sensor to your car's electrical system. Be careful not to nick nearby components.

Step 3: Remove the old oxygen sensor.

Get your hands on a wrench or a sensor removing socket to unscrew this component from the exhaust pipe. Most sensor types can be removed with an SAE 7/8-inch wrench, although it's best to consult your car's manual on what type of tool is best used.

Step 4: Check the new sensor if it has a built-in electrical connection.

If it comes with its own electrical connection, then you just have to reconnect it to your car's electrical system. However, if the new sensor is not equipped with its own electrical connector, you can reuse the old sensor's connector. You just need to cut out the connector from the old sensor, strip the wires, and attach it to the new sensor with butt connectors. To completely seal the connections, tape the wires up with strips of heat-sensitive shrink tape. Then take note of the manufacturer's instructions to know which wires should be tied together.

Step 5: Install the new oxygen sensor.

Screw the new sensor in place by using a wrench. Twist it counterclockwise to lock it in place. Make sure not to overtighten the sensor to prevent damaging the threads. Then plug the new or reused electrical connectors into your car's system.

Step 6: Clear the diagnostic code from your vehicle's ECU (engine control unit).

Once you've installed the new oxygen sensor, switch on the ignition so you could clear the code from the vehicle's ECU by using the diagnostic reader or scanner. After clearing the code, the check engine light will automatically switch off. Take your car for a test drive; you should be able to experience immediate improvements in your car's overall engine and emission performance.

Question 4: What is a California emissions sensor? How do I know if I need one?

A: California emissions O2 sensor is meant for vehicles that are designed to meet California emission regulations. Such vehicles should have a sticker under the hood or on the driver’s door jamb that identify them.

Features:

• 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"  connectors and harness
• Base ceramic probe of Zirconium and Yttrium: Forms a tough base that resists cracking from mechanical and thermal shock

?

?Fitment:

2004 Subaru Legacy 2.5L
2004 Subaru Outback 2.5L

FAQ of oxygen sensor:

Question 1: Do I need to replace all of my oxygen sensors at once?

A: It is best to replace your sensors in pairs. For example, if you replace the downstream left sensor, you should also replace the downstream right. However, on most vehicles produced since 1996, replacing one sensor (especially the front engine monitoring sensor) will cause the ECU to set a code for the other sensors. 
This is because the new sensor switching activity is much faster than that of the older aged sensors. It is probable that on most vehicles, the code will be set within 30-60 days AFTER the first sensor replacement.

Question 2: How do I locate specified sensor locations (B1S1, downstream left, etc.)?

A: Left and right sensor positions are found in reference to the rear of the engine (the side opposite of the belts).
Upstream (pre-cat) and downstream (post-cat) are found in reference to the catalytic converter. 

Question 3: How to replace an oxygen sensor?

Step 1: Locate the oxygen sensor.

This sensor is usually located on your vehicle's exhaust pipe. If you see something attached to the pipe that looks like a spark plug, then you've found the sensor. You can also consult your car manual since the sensor's exact location depends on your vehicle's make and model.

Step 2: Disconnect the sensor's electrical wires.

Use screwdriver to pry the tabs that connect the sensor to your car's electrical system. Be careful not to nick nearby components.

Step 3: Remove the old oxygen sensor.

Get your hands on a wrench or a sensor removing socket to unscrew this component from the exhaust pipe. Most sensor types can be removed with an SAE 7/8-inch wrench, although it's best to consult your car's manual on what type of tool is best used.

Step 4: Check the new sensor if it has a built-in electrical connection.

If it comes with its own electrical connection, then you just have to reconnect it to your car's electrical system. However, if the new sensor is not equipped with its own electrical connector, you can reuse the old sensor's connector. You just need to cut out the connector from the old sensor, strip the wires, and attach it to the new sensor with butt connectors. To completely seal the connections, tape the wires up with strips of heat-sensitive shrink tape. Then take note of the manufacturer's instructions to know which wires should be tied together.

Step 5: Install the new oxygen sensor.

Screw the new sensor in place by using a wrench. Twist it counterclockwise to lock it in place. Make sure not to overtighten the sensor to prevent damaging the threads. Then plug the new or reused electrical connectors into your car's system.

Step 6: Clear the diagnostic code from your vehicle's ECU (engine control unit).

Once you've installed the new oxygen sensor, switch on the ignition so you could clear the code from the vehicle's ECU by using the diagnostic reader or scanner. After clearing the code, the check engine light will automatically switch off. Take your car for a test drive; you should be able to experience immediate improvements in your car's overall engine and emission performance.

Question 4: What is a California emissions sensor? How do I know if I need one?

A: California emissions O2 sensor is meant for vehicles that are designed to meet California emission regulations. Such vehicles should have a sticker under the hood or on the driver’s door jamb that identify them.