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Cleaning the MAF sensor on a Corolla

According to some Toyota forums, cleaning Mass Air Flow (MAF) Sensor can fix low idling. At about 85,000 miles my Corolla’s idle speed decreased from 700 to about 500rpm and felt like it was going to stall sometimes after the AC compressor kicked off. Cleaning the MAF sensor seemed to have done the trick and it was a simple procedure that took no more than five minutes.

[update 5/7/14] – Corolla now has 147k miles and the low idle issue returned worse than ever. This time cleaning the MAF sensor didn’t help, so I removed and cleaned the throttle body which was pretty dirty and that fixed the problem.

Cleaning the Throttle Body:

You can do a quick in place cleaning of the throttle body without removing the assembly from the car, but this is somewhat difficult. Also, there’s the danger of losing the tb cleaner spray straw inside the tbody assembly or intake of the car. If that happens to you, you’ve got a lot more work to do. Basically a good first step in determining if your car needs to have the throttle body cleaned is to disconnect the air hose and have a look at the throttle body opening to asses how dirty it is. If it’s REALLY dirty (covered in black gunk) then removing it completely and cleaning it while removed is the best option. Here’s a reference picture of what a clean throttle body looks like:

clean-throttle-body-opening-corolla-2003-2004

Here’s a video on how to remove and clean the throttle body completely: https://www.youtube.com/watch?v=nKM6t1517AU

[equipment]

  1. Spray can of electronic components cleaner.
  2. Philips head screw driver.

[step 1] Locate the MAF sensor on the air filter box in the engine compartment. Disconnect the electrical connector and remove two Phillips head screws holding the sensor in place. Now wiggle it out carefully.

DSC00109

[step 2] Liberally spray cleaner over the visible sensor (but be careful not to touch it with your hands) until any dust buildup has been removed.

Toyota Corolla MAF Sensor

If you look inside the bottom opening of the component (where the circular hole is), there is a 2nd sensor  deep inside the plastic housing. Spray cleaner into the housing to remove dust from this sensor as well, but be careful not to touch the sensor with the straw of the spray can, it can easily be broken or damaged.

[step 3] Let the MAF sensor dry for a few minutes and re-install.

That’s it. Hope it helps someone else.

February 16, 2010

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21 comments found

Comments for: Cleaning the MAF sensor on a Corolla

  1. jonathan

    bueno deseo compartir mi historia hoy 25 de octubre de 2010
    tengo un hyundai tiburon 2006 tengo un filtro de hongo cai injen y tiene una bolsita dike hydro shield soy de panama y llueve mucho pero me confie y pasaba no por hynundaciones perso si por charcos y manejaba muy rapido por fuertes lluvias hasta el dia de hoy que mi carro presentaba fallas al aceleradar y subir lomas inclinadas keria como apagarse llegue rapido a mi casa y cometi el error en acelerar el carro varias veces hasta que se me apago……

    luego kise prenderlo y no encendio y boto gran cantidad de humo blanco por el escape. me asuste mucho temiendo lo peor revise bujias estaban secas kite el filtro y estaba humedo lo seque con un blower de peinar esas que usan las mujeres……el carro prendio pero al acelerar el motor al aumentar las revoluciones intentaba apagarce asike busque por internet y mencionaron el sensor de oxigeno. asike lo kite y efectivo tenia residuos de agua asike probe y lo seque con el blower y luego lo puse y limpie la tuberia del cai ya que tenia gotas de agua dentro. ecendi el carro lo acelere y acelero los rpm normal. sin ningun fallo…..solo me toca mañana probarlo en calle aver…..

    1. Steve Martin

      David,

      Worked like a charm. Thanks for the very complete and accurate description of the process.

      Steve

      1. bre808eze

        Can you do this without taking out the sensor? I have a 2000 Corolla and I can see/ these sensors when I take out the air filter.

        1. Calmira

          I’s not a good idea to clean without taking the sensor out. Honestly, it will take you a total of ten minutes to take out, clean, and put it back.

          here is a step by step: http://spydermagazine.com/2002/March/maf_clean/maf_clean.htm

          hope that helps

  2. Travis

    David,

    My engine light turned and when I connected my code reader it was a P0171. So I new my system was too lean. I found this website and figured I would try to clean the MAF sensor first since it was the least expensive option. It worked great so far. However, instead of buying electronics components cleaner, I purchased Mass Air Flow Sensor Cleaner. It was $6.99 at the auto parts store. It may be a little more expensive then electronic components cleaner but not sure.

    Travis

    1. Post author: 
      David Vielmetter

      Travis,
      The problem is that your MAF sensor wasn’t completely dry when you re-installed it. It has happened to me a couple of times and all I needed to do was leave it to dry out a bit longer. Then of course I had to reset the stupid check engine light by disconnecting the battery for 10mins and then had to re-program all my radio stations. MAF sensor cleaner is essentially the same as electrical parts cleaner (I think – please don’t quote me on that). It’s a fast drying liquid cleaning compound that shouldn’t leave residue behind. Try resetting your check engine code and see if it comes back. If it does, your MAF sensor probably needs replacing…otherwise it was probably just wet when you put it back.
      David

      1. monching22

        what if i disable my maf sensor?

        1. Post author: 
          David Vielmetter

          If you disable your maf sensor you’re asking for problems:

          – at best, you’ll get a constant check engine light.
          – at worst you’ll cause permanent damage to your emission system.

          Wouldn’t ever recommend disabling any sensor on the corolla.

          David

      2. Renee

        I have a 2006 Toyota Corolla and my check engine light just came on. Car has just shy of 85000 miles. I will have to take my car to a mechanic. Just curious if you know approx cost for how much the MAF cleaning and or repair you mentioned in your post of 2010 costs. Thanks in advance.

        1. David Vielmetter

          Hi Rene,

          The most common cause of check engine light on corollas is when the
          gas tank is not sealed properly. It happened on my Corolla several
          times. Basically it’s when the gas cap isn’t tight enough and when the
          tank gets low air gets sucked in.

          This is a very minor problem but the onboard computer will cause the
          check engine light to come on and will store an error in the computer.
          A mechanic can read these errors and will know what they mean and how
          to fix them…but they usually charge for a diagnosis. Here is what I
          do to determine if the check engine light is a real problem or just me
          not having sealed the gas tank properly:

          1. Turn the car off.
          2. Open the hood.
          3. Remove the positive connector on the battery for 5 minutes.
          4. Check to make sure your gas cap is tightly sealed.
          5. Reconnect the battery.

          This will clear all errors from the onboard computer and should clear
          the light. If the check engine light comes back, you may wanna take
          your car to a mechanic. If it does not, you saved yourself a diagnosis
          charge.

          Cheers,
          David Vielmetter

          1. David Vielmetter

            Note, disconnecting the battery will also reset all your music stations on the radio which sucks. So you can also buy an obd reader for 20 bucks on amazon and reset the check engine light was the that.

  3. Adrian Ahuja

    Thank you!!!!! Cleaning the MAF that work my car was diying if you was pressing the gas paddel for fast take off after I cleaning check engine light when off; before I cleaning I have codes for Oxygen sensor & ramdon misfire but I check sparks & was fine; like I said after I cleaning all the codes when off; do not forget to unplug the battery for few minutes to reset the engine computer.

  4. Tiffany

    Hi there your info regarding the MAS sensor on a 1993 corolla was helpful, however on our 93 corolla we cannot locate where it is and the picture does not give us enough info.

    Thank you Tiffany Zuck

    1. Post author: 
      David Vielmetter

      Hi Tiffany,

      Unfortunately I have no idea where the MAF sensor is located on a 93 corolla. Mine is a 2004 and I know where to find it on models 2003 and up only. Perhaps take it to your mechanic and ask him.

      Cheers,
      David

      1. selva

        Latest cars that controls by computer has the MAF sensor in the Air box ( I am not sure about 93 corrola But only thing I know is previously they used MAP (manifild air pressure sensor) and lately they are usinf MAF manifold aire flow, Can be found between the air filter box and manifold maninifold. In my 2000 corrola it is in the Air box. It has 4 wires connected. twowires goes to a themo couple to sense temperature and other two fine thin heating wires. those heating wires were covered with calcium like dirts. first I thought those dirts were part of the sensing system. after i cleaned I realised that sensor is just two metal heating wire and nothing else.

        I also amazed how these flow sensor works. computer sends a voltage through this elements to keep the elements at certain temperature. as the flow increases it needs more current to keep the temperature constant . computer calculate the flow by measuring the current and the air temperature.

        How you clean these wires are up to you. But keep in mind thes wires are very thin don’t damge it
        You will see a big differnce in performans after clean it
        Symptom of my trouble is
        1. PO 0171 check engine trouble code
        2. stumbles on accelaration
        3. Automatic tranmission chattering and jumping during accelaration ( this may not be a happening to every one)
        P:S- Keep a clean air filter before suspecting the MAF sensor

        1. d.a.

          selva
          you are right. before checking your MAF sensor make sure your air filter is clean . cleaning the MAF sensor will be useless if your air filter is dirty/plugged.

  5. Celso H. Silva

    Hello, I write from Brazil. I have a Toyota Corolla 1.8 VVTI 16V, and your problem is that even though with the engine warmed up, sometimes starts to fail as it was cold and then back to normal, eliminated from the list of possible problems the ignition coils as they would with the car failed the whole time, so I left the MAF sensor and my suspicions have declined even more about this sensor as recently disconnected the plug and connect the back and the car gave a sign of improvement. Does cleaning indicated by you will help me? Thank you. Celso H. Silva

    1. Post author: 
      David Vielmetter

      Hi Celso,

      I’m not sure if cleaning the maf sensor is going to help. You can take it out (it’s easy enough to do) and have a look at it with a flashlight. If it looks like it has a bunch of dust on it, then go ahead and clean it and let it dry for a good while before re-installing it. If it looks clean, then the MAF sensor probably isn’t the problem. If you have a low idle situation and it’s so low that the engine dies at idle sometimes, then most likely your issue is a dirty throttle body or clogged air filter or problem with vacuum lines.

      I found that with my 2003 corolla the thing that improved the low idle the most (before it was running 600rpm, now it is running 900rpm warm) was to clean the throttle body using some TB cleaner. While you’re at it, check all the vacuum hoses and make sure all of them are connected properly and the hoses aren’t leaking.

      Hope it helps,
      David
      D

  6. Ken Gust

    I read several different articles about the Mass Air Flow Sensor. In lieu of paying a certified mechanic to replace everything on the engine as he/they very much wanted to do, I purchased a can of MAF cleaner. I followed the procedure I selected to remove and clean the sensor. Prior to spray cleaning it I inspected it very closely and did notice a layer of black scum on one side of the glass temp sensor and two little black sensor probes deep inside the tube… I really didn’t know what to look for but I did see something. After using the cleaner liberally on everything, I re-inspected the probe and temp sensor and noticed that the glass temp sensor was clean on both sides and when I used a flashlight to look at the MAF sensor probes I noticed one of the probes that was uniform in shape and was light gray on the sensing part of the probe, it was the back one. The one that was toward the front was slightly de-formed and went from a light off white to a dark brown. It didn’t look right, like it had been fried, kinda like a burnt resistor on an electronics board. Hoping the cleaning would fix the badly running engine, I re-installed it, fired up the engine, and immediately knew the cleaning didn’t work. I decided that maybe the sensor was bad because of the one “burnt” probe that didn’t look as the other did. I went to two different auto parts places to find one and also experience some sticker shock. When I found a store with one in stock, I looked at the probes in the remanufactured one, and they both looked like the one good one in the old probe. When I installed the re-manufactured one and started the engine, it purred… how cool! The point here is, it took cleaning the sensor in order to see if the probes were OK. I now know what a good probe looks like and a bad one. If after cleaning the probes they look clean, are straight and uniform in shape and color, the probe is probably OK and ready to do the electrical test using a volt meter when running the engine if the engine still runs rough. I would recommend just replacing the sensor if after cleaning and inspecting it the probe(s) look burnt, brown and dirty. Take the old sensor with you as there is a $40-$55 core charge. Also compare the newly purchased one with the old one. The bad probe had 116K miles and was 13 years old.
    Good luck!

  7. KP Singh

    Hi..
    My self KP Singh, from INDIA. please help …

    I have corolla 2003 model and he is not getting start,there is fuel available .
    Can you advise me what are the reason and how can it start ???
    Please share all details on my Email..

    Thanks,
    KP Singh

    1. David Vielmetter

      Does it crank and just doesn’t run? Or does it fail to crank?

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