MAF Sensor Cleaning

If your car is running badly or it is just not as smooth as it used to be your MAF sensor could well be the cause.

How does a MAF Sensor work?

A brief background on what a MAF does. A MAF sensor measures the volume of air entering an engine by passing a current through a wire and varying the current to maintain the same temperature.

MAF Sensors are usually easy to locate and if they have done a lot of miles they could well benefit from being cleaned

The amount the current has to be varied to maintain the same temperature tells the ECU how much air in entering the engine.

Symptoms of MAF sensor problems and faults.

This article concerns a MAF sensor fitted to an Infiniti G20 / Nissan Primera GT P11. The symptoms of a dirty MAF sensor are as follows.

Uneven idle
General rough running
Uneven idle
Engine Surging slightly when cruising at steady speed
Engine suddenly losing and regaining power at light throttle openings
Inaccurate air/fuel mixtures
Erratic behaviour, sometime car is okay, other days car is almost undriveable especially when hot but also when cold

Why clean a MAF sensor?

I suspected a MAF problem so I called around to get a price for a new replacement. First of all it was difficult to track one down and second of all the price was over 400GBP. So I decided it was probably worth trying to clean the one I had.

How to remove the MAF sensor from your car.

In this case the car is old and the screws hold the MAF sensor unit to the main housing had corroded. Pliers were needed to remove the screws

First of all it has to be removed from the car.

This will vary depending on your car but it is usually pretty obvious where it is. It is located somewhere in the engines intake.

Once you have removed the section of the intake that holds the MAF you have to remove the sensor. Again this varies from car to car. In this case it was located with 2 screws. The head of the screws where severly corroded so a pair of pliers were necessary to remove them.

Once the screws were removed the sensor housing itself had to be pried away from the housing. On the G20/Primera it looks to be glued to the tube section so a flat head screwdriver was needed to prise apart the two components.

Once you have the 2 pieces seperted you can see the 2 wires that make up the MAF sensor unit.

In this case the wires were completely black, it was a suprise the engine ran at all! This sensor had been on the car for over 200,000 miles so the amount of dirt build up is not suprising.

To show how dirty the wires were, one is cleaned in this photo the other is not

How to clean the MAF sensor

To clean the MAF I used acetone and cotton buds. Acetone does not leave any residue behind when it dries and it does not effect electrical components so it is perfect for this use.

Nothing special about the cotton buds.

Cleaning is very straight forward, simply soak the end of the cotton buds and wipe the wires. Be extremely careful when cleaning the wires, literally just use the weight of the cotton bud, simply rest the cotton bud on the sensor and turn it slowly.

No force is needed, the weight of the cotton bud on it’s own is enough to clean the wires.

Using the weight of the cotton bud only is more than enough force to clean the wires

If you add anymore weight you will likely break the wires so be careful.

Reassembly of the MAF sensor unit

Once the wires are clean (in this case “clean” was judged to be when the wires were back to a silver colour), reassembly of the MAF sensor housing is obvioulsy the reverse of disassembly.

Stainless steel allen screws replaced the old items

One thing to note on reassembly is that because the MAF unit itself was glued to the tube section there was no gasket. To ensure there was an airtight seal I simply wraped the join between the two parts with electrical tape. This was the quick and easy solution, if you want to do a professional job you could obvioulsy sand down the glue on both surfaces to make them flat and reglue them together.

Electrical tape wrapped around join between MAF sensor unit and main housing. This is to ensure an airtight seal

Because the original screws were unusable I replaced them with some stainless steel allen key headed screws.

The old corroded screws holding the MAF sensor, these were replaced

One thing I should point out is that I don’t know if some MAF sensors have a special coating. If so, using acetone may well remove any coating. All I can say is in the Infiniti G20/Nissan Primera GT with a Hitachi MAF case the car was transformed by using acetone and after 500miles there is no reduction in engine smoothness so it appears everyting is working perfectly.

I personally recommend acetone to clean the MAF sensor

MAF sensor cleaning – YouTube videos

There appears to many videos on You Tube showing you how to clean your MAF sensor. From the videos I have seen none of them use cotton buds, they simply spray some substance on the sensor.

From my experience this is simply not enough to get rid of the dust and other deposits. Second of all a variety of products are used to spray the sensors. Personally, the only liquid I would recommend is acetone and not the acetone used for nail remover.

These are the cotton buds after they were used to clean the MAF wires. I am not convinced that simply spraying them with a fluid is enough to remove the dirt. As you can see the wires were completely coated in dirt and dust

MAF sensor cleaning summary

So all in all a very simple procedure that has cured all the running problems the car was having so a highly recommended procedure to carry out on your car if you are experiencing similar problems.

Of course, if you are unsure about anything get your sensor professionally cleaned.

This article is based in the cleaning of a MAF sensor on an Infiniti G20/Nissan Primera GT with Hitachi MAF sensor

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