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.


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


  • 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.

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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Comments 4

K Burch

October 16, 2018

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

CG Conner

November 2, 2018

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

FIXD Marketing

November 2, 2018

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


December 1, 2018

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.