Is it better to clean or replace a mass air flow sensor

I'm an online writer and proud owner of an Audi 1.8T. My articles focus on helping Audi and Volkswagen owners handle DIY projects.

Mass airflow (MAF) sensor

The Benefits of Cleaning Your Mass Air Flow Sensor

The more oil and dirt that accumulates on your MAF, the worse it serves its purpose. The dirtier it gets, the less accurate the reading it sends to your ECU (computer). These readings can cause lower gas mileage and a small loss of power.

Cleaning your MAF will not only extend the life of the sensor, but it will also help keep the power level and gas mileage where they should be. So, if you feel a lack of power when you hit the gas, or have noticed a change in your miles per gallon, the MAF sensor is the best place to start on your Volkswagen or Audi.

Parts and Labor Cost From the Dealership

A new MAF sensor from the dealership can cost anywhere between $80 and $150, depending on your car's make and model. The labor cost will add on another $150, as VW/Audi estimates the labor time needed is an hour and a half.

Recently, my new GTI needed a new MAF for emissions, as the old sensor was completely dead from the previous owner running the car with no air filter. I bought a new one on eBay for $40 that even came with a 90-day warranty; it has been six months, and I've yet to have a problem with it. So, if you're willing to trust an eBay product, that is also an option.

Doing this job as a beginner will take you around 30 minutes if you are replacing the MAF sensor, or around two hours (including drying time) if you decide to clean the sensor and put it back in. No special tools are needed for the job. It is very straightforward and easy enough for anyone to accomplish.

So why throw away $300 instead of doing thirty minutes of work?

Testing Your MAF Sensor

If you are already showing a "check engine" light on your dash, or you think you are feeling the symptoms of a bad MAF, here is an easy way to check the problem.

1. Unplug the MAF harness
2. Drive around

Yep, that simple. If you unplug your MAF and your car all of a sudden perks up, then the MAF is more than likely the problem, and cleaning the sensor is a great place to start.

Warning: If your check engine light is not already lit up when you try this test, unplugging the MAF sensor will cause it to illuminate. You can easily reset the light by unplugging the negative terminal on the battery for ten seconds (which is what I would suggest), or driving for sixty miles so the car can cycle.

If your check engine light is already on, then this is a great test to try, but before you try it, head to your local auto store and get a free scan. If they tell you that it is an oxygen (O2) sensor, then do this MAF test anyway, because an OBDII scanner can give false codes on VW/Audi and this test is a simple way to eliminate other causes for your check engine light.

Tools you'll need to remove and clean a mass airflow (MAF) sensor.

• Philips-head screwdriver
• Vise grip or pliers
• 91% isopropyl alcohol (rubbing alcohol), or MAF cleaner
• 2 trim replacement screws
• Gallon-size ziplock bag

The tools needed for this job are very simple. You should have most of them in your garage or tool drawer.

One tool that I have not listed is a specialty "tamper proof" five-star Torx bit made by and for VW/Audi. I've not listed it for three reasons.

1. This tool is incredibly hard to find, so it is not worth the price or hassle of ordering it from a VW/Audi dealership.
2. The screws involved can be replaced with Philips-head screws for future convenience.
3. These screws can be removed with pliers and once they're out you'll never have to deal with them again!

NOTE: Some MAFs use a 6-point tamperproof screw. If that is the case you can easily find a bit or screwdriver for those screws at any hardware or auto store for cheap.

The chemical that is used to clean the MAF sensor is completely up to you. There is a large variety to choose from at your local auto parts store, or you can use rubbing alcohol from the grocery store for about a dollar. I always use rubbing alcohol and have never had a problem. It cleans, dries quick, and is cheap. So for the cleaning part of this DIY, I will be using common 91% isopropyl alcohol.

Screws to replace the 5-point Audi Torx screws can be bought at any auto shop. I purchased a small pack of #10 trim screws from AutoZone for $2.29; they look just like the stock screws but with a Phillips-head tip. Another option is to just re-use the 5-star screws and put them back in the same way you took them out.

How to Remove the MAF Sensor and/or Housing

1. Unclip the harness connected to the middle of the MAF. The clip can be removed using your thumbnail. If it won't pop up, try a small screwdriver. Be gentle so you don't break the clip. Once you hear the clip pop, wiggle the harness off of the MAF. (All of the harnesses use the same type of clip, so once you learn how to release one, you can use that technique for coils or any other harness that needs to be taken off for repair. Here's how to replace a VW/Audi harness clip if you break it.)

2. Here you have a choice: you can either remove the sensor from the housing or remove the housing and sensor as a unit. If you still need to remove the 5-point tamperproof screws, I recommend removing the whole unit. Next you will need to remove the two Phillips-head screws connecting the MAF to the air box (on the right side of the MAF). Once those screws are out, disconnect the other side of the MAF from the turbo inlet pipe. Most VWs and Audis use pinch hose clamps, so use your pliers to squeeze the clamp open and slide off the inlet pipe. When putting the MAF back on, you can use a screw-type hose clamp to save yourself some hassle next time.

Slide the wire harness off of the MAF Sensor. Loosen the hose clamp on the left and the two screws attaching the MAF to the air box.

Push the large hose (TIP) off of the MAF housing and you can now completely remove the MAF from your car.

3. If you are choosing to remove the sensor only (which I recommend if you have regular 6-point Torx screws): Unscrew the two bolts in front of and behind the harness plug. Gently wiggle the sensor out of the housing. Skip down to step 6.

4. Once the housing unit is free, take your vise grips or pliers and pinch the sides of the screw connecting the sensor to the housing. (It can be a pain in the a**, but once you're done and replace those bolts you will never have to do it again). Grip it, turn counter-clockwise, re-grip it, and repeat till both screws are out.

5. The sensor is in nice and tight so wiggle it out of the housing.

Holding the MAF grip the sides of the screw tightly turning counter clockwise.

Wiggle the sensor free of the housing.

6. Once you wiggle the sensor out, put it in your ziplock bag and grab a beer. Victory is yours. The hard part is over (if you even want to call that hard!).

7. Fill that bag with rubbing alcohol and shake, shake, shake! If you are dealing with the sensor by itself, and not the housing, you can use a smaller bag with less alcohol, and use q-tips to clean off any left on residue. That's why I recommend taking the sensor out of the housing.

8. Once you're satisfied the sensor's clean, allow the parts to completely dry before re-installing and starting your car.

9. If you were dealing with the 5-point Torx screws, you can put the housing back in using the same method of using pliers on the sides of the screws, or you can replace the screws with the trim screws I mentioned above.

Time for the alcohol bath.

Volkswagen and Audi MAF Part Numbers

If you can add to my list, or have any corrections, please post a comment or send me an email.

K&N Filters, CAIs, Short Rams, and MAFs

This is always a huge debate.

Do K&N filters ruin mass air flow sensors?

In my opinion, yes and no. An over-oiled K&N filter will definitely coat, and, in the long run, ruin your MAF sensor, costing you a $100-$200 part. But a lightly-oiled K&N filter lets more air travel through your engine while still trapping dust and dirt particles, with no harm at all to your MAF.

I have used K&N filters in stock air boxes, short ram air intakes, and regular cold air intakes (CAIs) and I have never had a problem with them ruining an MAF sensor. To avoid problems, take one simple step: clean your MAF every 5-10 thousand miles. That preventative maintenance should be done no matter what type of filter you are using, oil or paper.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

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