OBD2 Codes

P0101 – Meaning, Causes, Symptoms, & Fixes


Code P0101 Definition

Mass Air Flow (MAF) Circuit/Performance Malfunction

Code P0101 Meaning

The mass air flow (MAF) sensor measures the amount of air entering the engine. Check engine light code P0101 is set when the measurement of air entering the engine by the mass air flow sensor is outside of the manufacturer’s specified range.

Symptoms of Code P0101

  • Engine stalling
  • Difficulty starting
  • Lack of power
  • Rough idle

Causes of Code P0101

  • Dirty, obstructed, or faulty mass air flow sensor
  • Damaged or disconnected air intake boot (snorkel)
  • Vacuum leak
  • Clogged or improperly installed air filter
  • Clogged catalytic converter / restricted exhaust

Code P0101 Severity – Moderate


Code P0101 does not pose any danger to the driver and will not prevent the vehicle from running. However, it will cause an increase in fuel consumption and rough operation. Sustained driving can lead to internal engine failure.[/vc_column_text][vc_row_inner][vc_column_inner][vc_column_text]

Code P0101 Common Diagnosis Mistakes

Buying and installing a new mass air flow sensor without completing the entire diagnosis process.

Code P0101 Diagnosis Steps

How To Diagnose P0101

  1. Locate your air intake box that houses your air filter. Open the air intake box using the required tools for your vehicle. Ensure the air filter is seated properly and is clean. Reseat the air filter if it is not seated properly, and replace the air filter if it is dirty. This may be as much as you need to fix P0101, however, we recommend completing step 2 as well. It is not difficult or expensive, and may improve performance. 
  2. Remove the wiring harness from the mass air flow sensor and remove the air intake snorkel from the air intake box. Use mass air flow sensor cleaner (DO NOT SUBSTITUTE FOR ANY OTHER KIND OF CLEANER) to clean out the MAF sensor. Do this by spraying each side of the MAF sensor for 3-5 seconds, waiting 10 seconds, and then spraying it again for 3-5 seconds. Do not wipe it. The MAF sensor hot wires are very sensitive, and MAF sensor cleaner cleans and dries very quickly. Reconnect the air intake snorkel, close the air intake box, and reconnect the MAF sensor harness. Clear the check engine light code using the FIXD app and complete several drive cycles to ensure this was the correct fix. Here is a great video to show you this process!
  3. If your check engine light comes back on with diagnostic trouble code P0101, examine the air intake system for vacuum leaks.
  4. If no vacuum leaks are found, it is likely a restriction in your exhaust.

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  1. Very helpful, never expected to have a way to remedy the problem given also. Very informative.

    1. Thanks,, this let’s me know what to expect when I take it to get repaired

      1. How can it be exhaust stopped up if MAF was making a gear noise

      2. First thing to do is check for recall regarding ECU reprogram.
        Check the condition of MAF.
        Clean or replace (if is necessary) the MAF
        Reset the code and make a test drive.
        If the code persists (sometimes check engine light is not on but the code is the) probably is time to reprogram the ECU.

        1. Roberto,
          Hi i am having the same issue with my vw passat b7. I’m keep getting fault code p0101 after changing air MAF sensor, checked air intake snortel plus wiring and even changed with new air filter. Before changing all these parts I was getting engine on as well but now it is only coil light comes up after 5 miles do I need to reprogram my car’s ECU.

    2. Thanks for information about the mfs. I will get my mechanic on it I will let you know what happens.

  2. So far we love our FIXD. We have already completed the job and now just waiting to see if check light comes back on again. I have a 1997 Miata that we know is running rich and it feels like it is miss-firing but no check engine light. Can FIXD help me diagnose issues without check engine light on? Can you help me with a reliable and honest mechanic in south Georgia/North Florida area that knows how to work on NA Miata? Thanks

    1. Hey Connor! Currently, FIXD only diagnosis when the Check Engine Light is on. In terms of finding a good mechanic, if you go to the tool bar on the right side of the app, there should be an option to “Select Service”. This will help you find a quality mechanic!

      Thanks, FIXD Team

      1. The 2011 Nissan Altima service engine soon light came on. The code says p0101 can anyone tell me what’s that mean. If not fixed what will happened.

      2. FIXD, I installed a cold air intake on my 2009 GMC Sierra 1500 SLE and had the P0101 code come up for the mass air flow sensor malfunction. I remedied all of the problems and my check engine light went away. But my fixd app sensor stills shows the code when I scan it. The code doesn’t go away but there is no check engine light. What should I do as I have had several mechanics take a look at it and I’m a mechanic myself and nobody can figure out why the code is still there. Does it just need to be driven around for a couple hundred miles? I have already driven about 250 miles since the light went away. Please help me.

  3. Didn’t pick it up on the fixd app directly, got this email. Did what I was instructed to do and the problem was however remedied which was nice.

    1. Thank you that was very helpful and inexpensive

  4. Very helpful, thanks for diagnosis steps because the MAF isn’t cheap but it made my car work again
    Thank you once again

    1. No problem Kevin! Glad we could help.

      FIXD Team

    2. What does MAF mean?

      1. Mass air flow

  5. Any help would be appreciated.
    Replaced my MAF censor, intake gaskets, catalytic converters, all 4 o2 censors, map censor, and wire harness for the maf. Engine light still on for maf. Has p0101 p0172 and p0175 codes. Not sure what to do next.

    1. Same here

    2. Sorry mine is a 2012 Nissan Maxima

  6. My 2004 S10 Blazer 4×4 with 95,000 miles has recently been difficult to start intermittently. After several weeks of the occasional hard/long start issues, the SES light came on and my FIXD showed this P0101 code.
    I cleaned my air filter and the MAF sensor and experienced no improvement. So, I then replaced the filter and MAS sensor. Unfortunately, I’m still having the same problems as before.
    Sometimes the vehicle starts right up and sometimes I must keep cranking it (or stop and begin cranking over again) to get it going.
    Any idea what I should do next or what might be causing my problem??
    Thanks. I love my FIXD!

  7. FIXD troubleshooter led me right to an improperly closed air filter box! Replaced the filter and cleaned out the box. Problem solved. Thanks

    1. Not an answer but a question, what code were you getting to be lead to this fix?

  8. as I had already replaced the MAF sensor before receiving FIXD – I connected it & it gave me the same diagnosis that I had already received from 2 other mechanics. I was able to turn off the check engine light – however the car is still rough idling and mpg still fluctuating between 11 – 34 ? any help on this? 2016 Nissan Sentra SV (I also replaced the air filter)

    1. Hi Heather, I wish I had an answer but I’m in the same boat as you with my 2012 Nissan Maxima. I did read in FIXD that if replacing filter and MAF sensor doesn’t resolve the issue it is either a vacuum leak or exhaust issue. If you have found a remedy please let me know.

      1. A vacuum leak will usually cause a lean code,and live air alpha percentages will be in the 120% higher ranges.Vacuum gauge is a very useful tool. If the engine combustion is balanced and no intake,exhaust,PCV. issues.A replacement throttle chamber a correct calibration setup should remedy.Also install any ECU. updates and clear all control DTC’s and clear ECU’s self-learned data.

  9. So I Asked the guy at autozone if he knew what it was NOPE!!!! Now I’m in here leaving this comment with a BIG THANK YOU!!!!

  10. That’s the code FIXD gave me. And, I don’t think this is what’s killing my battery. Seemed like a very good diagnosis, but what does that have to do with my battery, something is killing my battery. Turn off the car, and I might get under 10 minutes before I would need a jump

  11. Why is it important to use the MAF cleaner from Gunk and not another brand such as CRC?

  12. That sounds like a battery or alternator issue. I’d get a multimeter and check if the battery is at good voltage, it might be a dead cell.

  13. I used the Fixd reader to diagnose the problem with my check engine light. I then went to Autozone and purchased a can of Mass airflow cleaner for ten bucks and sprayed the sensor, waited a few moments and put it back together. I then used the Fixd reader to reset the check engine light, problem solved! In my opinion the Fixd reader just paid for itself, on the first use. I would highly recommend this product, no question about it a very worthwhile investment .It’s not very often a product will pay for itself in one use. Thank you.

    1. That’s awesome Pete! Thanks so much for the kind words and thrilled to hear how FIXD helped you with your car problem!

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