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Subaru Outback MAF Sensor Cleaning & Replacement Guide
How to clean or change the FB25 engine's mass airflow sensor in a 6th generation 2015 to 2018 Subaru Outback.

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2017 Outback FB25 2.5L
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Engine Air Intake Hose
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Subaru / Denso MAF Sensor

This automotive maintenance tutorial was specifically written to assist owners of the sixth generation (2015, 2016, 2017, 2018 and maybe also the updated 2019 and 2020 model years) Subaru Outback station wagon equipped with the FB25 2.5 liter four cylinder Boxer engine in removing, cleaning and replacing the MAF (mass airflow) sensor.

Owners of other Subaru vehicles such as the Forester, Impreza, Legacy, XV Crosstrek, WRX, BRZ, SVX, Tribeca, Exiga, Trezia, Levorg and Baja may also find these DIY instructions to be helpful.

The original (OEM) mass airflow sensor replacement part number is Subaru 22680AA38A (also known as 22680-AA38A).

A compatible replacement aftermarket sensor is the remanufactured Cardone # 74-50070 MAFS.

The only tool needed to remove and replace the sensor is a standard Phillips head screwdriver.

To clean the sensor, use a Mass Air Flow Sensor Cleaner spray.


Some of the symptoms of a faulty MAF sensor include a rough running engine, difficulty starting, stalling, hesitation, jerking and stalling.

If you have an OBD2 Scanner (also known as an OBD II Port Scan Tool), you may see the following error codes: "P0100 - Mass Airflow Circuit Malfunction", P0101 - "MAF Sensor Circuit Range / Performance or P0102" - "MAF Sensor Circuit Low Input".

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Loosen Counterclockwise
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Disconnect Power Plug
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Remove Second Screw
The first two steps are to open the hood and then move to the left (passenger side) of the engine bay.

The mass airflow sensor is located on the top of the air intake tube in between the engine air filter box and the left side of the engine.

It is held in place to the air intake tube by two Phillips head screws.

Push in the release tab on the electrical connector before sliding it straight off the base of the MAF sensor.

Remove the two screws by turning them in the counterclockwise direction with the Phillips head screwdriver.

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Two Screws Removed
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Pull Out MAF Sensor
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Bottom of Sensor Unit
Set the two screws aside in a safe place.

Gently lift the MAF sensor straight out of the air intake hose.

If you have trouble removing the sensor, try gently rotating it back and forth in the hole while pulling it straight out.

The OEM sensor was marked as Subaru part number 22680AA38A (or 22680-AA38A). It is also known as Denso part # MX197400-5131 03U22.



 

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MAF Wire - Side View
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Opening In Air Intake Tube
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Push In New MAF Sensor
To clean the old MAF sensor, first cover the electrical connection and the top of the sensor assembly with a plastic bag.

I recommend using CRC Mass Air Flow Sensor Cleaner spray since it has excellent reviews on Amazon.

Carefully spray the cleaner solution on to the exposed MAF sensor wire.

Do NOT touch the wire or use a brush. Simply spraying the cleaner on to the wire a few times at different angles is enough to remove the fine dust, oil or grease that might have contaminated the wire.

Allow the sensor wire to air dry. Do NOT use a can of compressed air or the blower setting of a wet/dry shop vacuum to dry the sensor since the high pressure air may bend and damage the delicate sensor wire.

Once the sensor is dry, re-insert it into the air intake tube.

Line up the two fastener holes on the sensor with their corresponding holes in the air intake hose.

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Tighten Screws Clockwise
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Push On Electrical Connector
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MAF Sensor Replaced
Replace the two screws by tightening them in the clockwise direction with the Phillips head screwdriver.

Try to avoid over tightening the two screws to prevent from cracking the plastic air intake tube.

Push the power plug straight into the socket on the base of the MAF sensor assembly until it clicks securely into place.

To test the cleaned or new MAF sensor, start the engine and look for any warning lights (Check Engine / CEL or Service Engine Soon / SES).

If you have an OBD II Port Scan Tool, check for any error codes and clear them. Then turn off the ignition and start it again to see if the codes re-appear.

If the MAF sensor related diagnostic error codes re-appear, you may need to buy a new MAF sensor.

Be sure to record the MAF sensor cleaning or replacement in your vehicle's service records.

For more, please check out all of my 2015-2018 Subaru Outback DIY Repair & Maintenance Guides.
 

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