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2013 2.5i Premium 6mt, Twilight Blue
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Discussion Starter #1
The Mass Air Flow (MAF) Sensor measures the flowrate of air through the air intake before reaching the engine. Since the density of air changes with temperature and pressure (due to ambient temperature, altitude), the ECU needs this information to provide the correct fuel mass to the engine.

So WHY is it important to clean the MAF Sensor? Over time, dust and oil particles will stick to the hot wire (what measures the flowrate of air) and essentially "bake" on and distort the measurement. The result can be rough idling, poor acceleration and engine starting, and overall worse gas mileage. Cleaning the MAF Sensor can remedy or avoid these symptoms. Also, you can avoid the costly replacement of the MAF Sensor by cleaning it regularly. I usually clean mine at every oil change interval - doing it is quick, easy, and cheap.

Equipment needed: CRC Mass Air Flow Sensor Cleaner (available at any auto parts store, costs about $9. or right here on Amazon for 9$)
Tools needed: Philips head screwdriver
Level of difficulty: Low
Time needed: 5 minutes

CRC Mass Air Flow Sensor Cleaner:

Open the hood and locate the MAF Sensor, on top of the air duct between the air filter and throttle body, circled in blue here:

Disconnect the wiring harness, remove the two screws and carefully pull the MAF Sensor from the housing. Then, spray the MAF Sensor with the CRC. The hot wire (circled in blue below) is the important part you need to clean, but I usually just douse the entire piece with CRC to remove all particulates. Just be careful NOT to touch the wires - just hold it by the part where the wiring harness was connected as shown below. The cleaner will evaporate in a few seconds; let it completely dry before reinstalling (carefully reinsert the sensor, attach two screws and connect wiring harness). And you're done.
 

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2006 WX8: my "Outback" > yours
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978 Posts
How much contamination was found on the wire? Just curious, because a hot-wire sensor is supposed to go through a self cleaning cycle on start-up.
 

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2013 2.5i Premium 6mt, Twilight Blue
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2,378 Posts
Discussion Starter #3
^ If you clean the wire often enough any buildup of contaminants probably won't be visible to the naked eye, but there could still be microscopic particles on the wire.

A hot wire burn-off cleaning circuit is used on some sensors, but as far as I know the Subaru MAF Sensor does not have this feature.

Anyway, this DIY is so cheap and easy it's safer to do it every 3k or 7k miles than have to replace a burnt out MAF Sensor (about $150).
 

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Lawn ornament XT
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I'd like to add a cautionary note- improper cleaning or handling during cleaning can harm the MAF. Cleaning it more frequently adds more handling, more chances to screw up an expensive part.

Given that many drivers will plow through 100k miles without any MAF related symptoms, it is worth balancing the performance of a perfectly clean sensor against the risk of overhandling the parts.
 

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2013 2.5i Premium 6mt, Twilight Blue
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Discussion Starter #5
^ That's fair; as with any self-performed maintenance there is always the chance of doing more harm than good. That being said, the OB's MAF Sensor is one of the "safest" to clean compared to other cars I've worked on in that the hot wire is mostly protected by plastic. One would have to TRY to touch the wire in order to make contact.

And, although the MAF Sensor may not fully break over XXXX miles, owners can still be unknowing victims of poor acceleration and worse gas mileage due to a dirty MAF Sensor.
 

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2006 WX8: my "Outback" > yours
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The Bosch-style MAF sensor originally used on EJ/EG engines was self-cleaning and I don't recall any discussions about cleaning those. If the current type isn't self cleaning, that's another small step in the process of cheapening up and general toyotazation.
 

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2013 2.5i Premium 6mt, Twilight Blue
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Discussion Starter #7
The Gen 4 OB's MAF Sensor is made by Denso, and from my research I have not seen anything that leads me to believe the Outback's MAF Sensor is self cleaning. Even if it was, I would still clean it regularly to ensure the entire part was clean and not just the hot wire.

My BMW did not have a self cleaning MAF Sensor, so I would be surprised if Subaru sprung for it on their lineup.
 

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2013 Outback 3.6L Limited with EyeSight
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218 Posts
I clean the MAF sensors in all my vehicles every 18 months. Pouring rubbing alcohol over the 3 small delicate elements also works (along with electronic parts cleaner).
 

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Totally reviving an old thread here, but I just cleaned the MAF on my 05 Outback XT (with 56k on it). It's probably the first time it's been cleaned since it was purchased, and it made a big difference!

I was having some shaky acceleration at certain speeds, and the CEL came on at one point, prompting me to replace the upstream o2 sensor. That made the acceleration a lot smoother, but something still felt off. Pretty stoked that a 5 min. job made my driving experience so much better. How often do you normally clean the MAF?
 

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2011 Outback 2.5i Premium, CVT, Steel Silver, all-weather package. Upgrades: Tweeter kit, BlueConnect, media hub, remote start, Curt 2" receiver hitch.
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I clean the MAFs on all of our cars at each oil change.

We had a number of diesel VWs in the family, and certain years had problem with MAFs. Apparently, it was a HUGE batch of bad MAFs, and VW was charging about $400 for them. They redesigned the MAF and lowered the price to about $180, but never admitted there was a problem. I replaced a few of them. Cleaning them never seemed to help, but I did learn a few thing about MAFs along the way:

1) They should be cleaned periodically.

2) Never use ArmorAll or similar products around your intake... it could lead to premature MAF failure.
 

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2014 Outback 2.5i Limited with Eyesight
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So I went to clean my MAF sensor at ~23000 miles and the O-ring was broken. Tried to look up the part but as best I can tell, the O-ring is just considered part of the sensor. Meaning there's no part number I can order to just switch out the O-ring. Anyone have any thoughts on the issue? Think Subaru's warranty will cover it or are they gonna give me a hard time?
 

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Thanks for the info on the MAF cleaning. Question...how do I unclip it? Do you pry up the tab or push down on the middle part and then pull? I don't want to bully this part too much.

Thanks.
 

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2019 Subaru Forester Premium, Crystal Black Silica, Pkg 15
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Just cleaned mine on my 11 2.5 with 75k on it. Thanks for the guide! Seems to idle a little smoother now. Will test on way to work tomorrow.
 

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2001 Subaru Outback 2.5L 5 Speed Manual.
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The Mass Air Flow (MAF) Sensor measures the flowrate of air through the air intake before reaching the engine. Since the density of air changes with temperature and pressure (due to ambient temperature, altitude), the ECU needs this information to provide the correct fuel mass to the engine.

So WHY is it important to clean the MAF Sensor? Over time, dust and oil particles will stick to the hot wire (what measures the flowrate of air) and essentially "bake" on and distort the measurement. The result can be rough idling, poor acceleration and engine starting, and overall worse gas mileage. Cleaning the MAF Sensor can remedy or avoid these symptoms. Also, you can avoid the costly replacement of the MAF Sensor by cleaning it regularly. I usually clean mine at every oil change interval - doing it is quick, easy, and cheap.

Equipment needed: CRC Mass Air Flow Sensor Cleaner (available at any auto parts store, costs about $7)
Tools needed: Philips head screwdriver
Level of difficulty: Low
Time needed: 5 minutes

CRC Mass Air Flow Sensor Cleaner:

Open the hood and locate the MAF Sensor, on top of the air duct between the air filter and throttle body, circled in blue here:

Disconnect the wiring harness, remove the two screws and carefully pull the MAF Sensor from the housing. Then, spray the MAF Sensor with the CRC. The hot wire (circled in blue below) is the important part you need to clean, but I usually just douse the entire piece with CRC to remove all particulates. Just be careful NOT to touch the wires - just hold it by the part where the wiring harness was connected as shown below. The cleaner will evaporate in a few seconds; let it completely dry before reinstalling (carefully reinsert the sensor, attach two screws and connect wiring harness). And you're done.
I just wanted to say thanks for this thread. I recently threw a check engine code saying Bank 1 was running lean, after finding this thread, cleaning my Mass Air Flow sensor and clearing the ECM I have no more CEL and the car feels much smoother. I'm about 100 miles in with no return of the CEL. Thanks for helping me out guys!
 

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2007 EDM H6
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Ordered a LiquiMoly MAF Cleaner, only one I could find locally, I suspect the concept of "MAF Cleaner" could be mostly marketing, it could be a repackaged version of another cleaning product, but unimportant

Thanks for sharing this, very curious about my own results, I agree with @rasterman too, but If I was experiencing MAF issues I would likely try this first, even if it extends the life of the MAF sensor until the replacement arrives, it would be something
 

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Stuck 500miles from home with a P0172 CEL and stalling at stops. Going to give this a shot and report back. Didn't want to start a new thread just for myself. Have already read through many threads and am pretty stressed out. Hope this works!
 

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$12 and probably 15min of my time, ditched the oily K&N air filter, put in a new paper one, pulled the MAF sensor and cleaned it a few times. Definitely dirty and cleaning it made it look like new. Hasn't stalled yet, but will update this weekend after get home and I have put 500mi on it.
 
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