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P0101 – Meaning, Causes, Symptoms, & Fixes


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What Does Code P0101 Mean?

  • P0101 definition: Mass Air Flow (MAF) Circuit/Performance Malfunction
  • Issue Severity: MODERATE – Extended driving with this code can cause internal engine damage.
  • Repair Urgency: Get this code fixed as soon as possible to avoid internal engine failure.
  • Diagnosis: 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.

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.

P0101 Causes

There are many potential causes of code P0101. Some are easy to check and correct yourself, such as a dirty air filter or mass air flow sensor. Other causes are more complicated, such as a vacuum leak or a clogged catalytic converter.

  • 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

P0101 Symptoms

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

How Do I Fix Code P0101?

With a mass air flow sensor fault, the first step is to get it diagnosed to figure out what is causing the problem. 

If your vehicle has this fault and you’re not comfortable diagnosing this issue at home, we recommend finding a RepairPal certified shop nearby to pinpoint the problem and give an accurate estimate for repairs. 

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

How Much Does It Cost to Fix Code P0101?

P0101 can be caused by anything from a dirty air filter to a clogged catalytic converter. It’s impossible to give an accurate estimate without properly diagnosing the issue first. 

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0101 code.

Possible Repair Costs for P0101

Once properly diagnosed, P0101 may require one or more of the following repairs to resolve the underlying issue. These prices are based on national averages and include parts and labor. Your cost may differ depending on your location and type of vehicle.

  • Air filter $50-70
  • Mass air flow sensor $220-320
  • Catalytic converter $1720-1780

DIY Steps to Diagnose Code P0101

Engine code P0101 could be caused by a number of things, including a dirty air filter, mass air flow sensor, catalytic converter, and more. If you’d like to try to fix code P0101 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Keep in mind this is an intermediate-level diagnosis and repair and not recommended for beginners. Diagnosis beyond oil level and condition requires more specialized equipment beyond what the FIXD Sensor can provide and it can be a time and labor-intensive process for inexperienced DIYers.

DIY difficulty level: Intermediate

This repair requires mechanical knowledge and is not recommended for beginners.

Tools/parts needed (our top picks from Amazon):


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. 


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 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!


If your check engine light comes back on with diagnostic trouble code P0101, examine the air intake system for vacuum leaks.


If no vacuum leaks are found, the problem is likely a restriction in your exhaust. This could be a clogged catalytic converter, or physical damage to the exhaust itself, causing a restriction that prevents exhaust gases from flowing out of the engine smoothly.

Common P0101 Diagnosis Mistakes

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

Still Need Help Fixing Code P0101?

If you’ve followed the steps above and are still experiencing check engine code P0101, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.

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Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

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About the Author

Justin Hughes

Justin Hughes

Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

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