Passat MAF, problems with the MAF sensor, Mass Air Flow meter


RBK la Muntele Rosu
Last days, RBK ( Rebe ), my old faithful Volkswagen Passat TDIRBK la Enisala  show some signs of weakness. Symptoms: Suddenly loss of power. Car, very lasy! The car didn’t accelerate as it usually does and with the gas at full, yon need a century to go up at 100 – 110 km/h. ( 62 mph ) The engine go up to 2000 rpm then hold around there, and no further.
Ok, first think, maybe it was the gas filter or, god, hope not, the turbo is broke or jam.
But normally the turbo didn’t broke easily at this cars, and the filter was new, so let’s check the sensors chain. I wrote this small tutorial with images to teach step by step maf replace.

VW Passat MAF location locatie
With vagcom and a cable it was easy to diagnosticate, but I have not those things. (Today i have! I made for my self a vag-com cable. )
So without proper equipment, let’s try step by step. Take some Spice from Dune and with the help of The Force i start with the MAF Sensor. His location as show in pictures, is just after the air filter.  So I chose the easiest way to test your maf.
The very easy way to diagnosticate this sensor is to pull out the just the cables and test the car on VW Passat MAF location locatiethe road. If the car run in the same way, or even better, you can be sure, the MAF sensor is gone. That’s exactly what I did and the car accelerate better without the MAF connected.
Hurray, is not the turbo! The MAF is broke.
The MAF, Mass Air Flow meter is the sensor who indicates to the ECU (car computer)  the air mass who flow inside the engine.

VW Passat MAF sensor senzor close-up
I take it out, and try cleaning. Usually if is not completely burn out, a good cleaning with isopropylic alchool can do the job.
But not ever think to touch the sensor itself with something, like paper or a stick with cotton. Just alchool or clear, very pure contact spray for electronics.
Don’t spray directly on the sensor. The power of the spray jet can damage it. The best way is to immerse the sensor part in isopropilic alcohol and let it about 30min with gently shake from time to time. Please, DO NOT open the sensor, do the cleaning with the sensor as it is, unless you have nothing to lose and you are prepare for a new one!!
 
VW Passat MAF sensor senzor close-up
If this treatment do not restore the MAF sensor,
VW Passat MAF sensor senzor close-up
maybe is time to buy a new one. If you have BOSH, you can buy also a Pierburg one, is (at least here) much more cheaper and work great.
On my old BOSH MAF I do a autopsy and I put the pictures here and a repair tutorial. Remember this sensor is burn out, do not open yours.
The MAF sensor work by heating a small filament at a certain temperature. With the air blowing over, the temperature drops. So the filament need more electricity to rise up the temperature. The ECU measure the power needed to keep the temperature, and estimates the mass of the intake air.

Pierburg, Bosh and Vader
MAF defects can show because the dust from the air, or more often from microscopic drops of oil, especially if you have sport air filter, with oil.So, the conclusion: if you have Volkswagen Passat TDI, or Skoda TDI, or anything TDI with MAF sensor, if your car lacks power is lasy, do not panic.
First, disconnect the MAF and test the car. If the car runs nor badly but the same or even better, then you know, is most probably the MAF.

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112 comentarii

Din categoria Auto, Uncategorized

112 răspunsuri la „Passat MAF, problems with the MAF sensor, Mass Air Flow meter

  1. Seb

    Hi all, and especially Vale.
    I would like your advice on a problem that I frequently have with my VW Polo 1.4 2000. In summer the car runs great. In winter, and especially when it’s wet, the car shakes a little. When it rains heavily, the car suddenly looses power (can’t go above 110-120 km/h), all lights on the dashboard start blinking and sometimes the engine temperature indicator goes down to < 70 C. If I stop and restart, the shaking stops, and the lights and indicators are all ok. My VW dealer has replaced spark plugs etc but it doesn't make any difference. I wonder if the problem is something electronic. Any idea? Thank you

    • jhana c

      I „think” for 2000’s, VW was still placing the transmission control modules (TCMs) under the passenger side floor. After who knows how many replacements that VW took responsibility for, they stopped placing them there. The reason they were replacing them is because there would be a build up of water surrounding the TCM in its passenger for location. You say this only happens in wet weather, the TCM and the components around it may be to blame if the placement is the passenger side floor? That would also explain the blinking lights and loss of power, because both of those things stopped when I replaced mine a few months ago. I would try to get a free diagnostic test first and foremost. If TCM is the issue, check EBay, there are some good sellers on there, in my case, I paid 70% less than the dealer wanted, not to mention, the money they wanted for install. Check YouTube for videos, I have NO knowledge on how to do this job but it took me 2 hours with a couple of videos and basic tools. Also, others who have replaced TCMs that were under passenger floor have not put them back in the same spot but instead have mounted them under the actual passenger seat (inside the main cabin of the vehicle-where it’s normally dry) and have secured it with everything from dealership or makeshift mounts, ask the way down to cable ties to prevent the same problem from happening again. I hope this helps. You can do the job, do not pay mechanics or dealerships for relatively simple jobs that they try to scare you out of doing yourself. These cars are not as difficult as everyone makes them seem and you have got only time to lose, and money and experience for the next time around to gain.

    • Hi Seb!
      Sorry for your VW problems. Obviously it’s a thing related to of humidity or water built up somewhere and I second Jhana’ s detailed opinion about TCM (transmission control module) on VW because it’s a relatively frequent problem on older VW’s with this sensor taking water, so check this first. If it-s running well on dry weather chances are that TCM module is not definitely damaged. Clean all the (eventually) corroded connections (here WD40 help). Also check for clogged water drains under the battery and the gasket below the pollen filter. At old cars this gasket get cracked and let the water inside car. And if you really need to change TCM, buy one used from auto spare parts shops. Carefully with the part number to be the same. Good luck.

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  5. Billy

    I have a 99 vw passat 1,8 turbo. Beautiful car. When I originally bought it, it was not running. long story short the CCM was under water. Bought a new one and got a throttle body alignment. The car still didnt run very good. I hooked up to a VAG COM and it is indeed my maf. I have taken the MAF and cleaned it thoroughly. It looks brand new. The resister in there is blue and looks perfect. I am thinking I need a new one but I dont want to buy one if I am not certain thats what it is. I unplugged the sensor car ran fine and everything I know it has something to do with the maf i just dont know if it is a wire or the actual sensor. am I able to hook an ohm meter to each individual wire? if so, what voltage should I read on each wire? Thanks. Any advice will help tremendously.

  6. mike

    please i have a 2002 Volkswagen passat but is very sluggish most tim es idle and does not fire well vibrates and shuts like a gun sound.i have change the plugs changed two coils changed the airflow metre even the fuel pump and still experiencing these serious heart braking embarrassing problems please kindly help out

    • Hi Mike!
      Sorry to hear that. One important question is the engine type and/or code, or, at least, is your car on disel or gas?
      But anyway my guess is that those symptoms come from one or more cilinders that don’t have ignition. The way it virbates, lack of power and the rough idle is specfic for that . Also, when the unburn fuel from the dead cilindre(s) is evacuated in the evacuation pipe, then it ignite there, so there you have the loud bangs. So look for the injectors, plugs, nozzle or bad compression. Other probable cause: similar problems can come from a bad adjusment or defective timing belt.
      Hope this help, good luck!

  7. mike

    hello everyone,please i have a passat 2002,running on fuel and also automatic drive,but it doesn’t move when it changes from gear 1 to 2,even climbing a not too high hill,but accelerates very well when on park,please could it be a low pressure fuel pump or a am i to change the gear entirely or could it be the drive clutch on the gear,please i need insights from anybody ,as changing gear here in Nigeria is quite expensive

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