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Check Engine Code P0101: Mass Airflow Sensor Error

Learn How to Diagnose and Fix this MAF Error Code

So your check engine light came on and your OBD2 code reader returned a P0101 error? That’s the check engine light code for a Mass Airflow or MAF malfunction. Simply put, your vehicle may be getting too much airflow or too little. Either way, you may notice that your car is running a little rougher than usual. This is an issue that needs to be investigated and resolved quickly. Over time, improper airflow can damage your engine and make this relatively inexpensive fix a whole lot more costly.

For more information on OBD2 code scanners, check out our blog, How to Use an OBD2 Scanner.

First, let’s break down the code for a MAF error and what the digits mean.

P0101 definition: Mass or Volume Air Flow Circuit Range/Performance Malfunction

P – Powertrain (The letter identifies which system houses the malfunction.)
0 – Standardized Code (The first digit identifies the type of code. Standardized means it’s the standard for all vehicles that use OBD2 readers).
1 – Air and Fuel Mixture Issues (The second digit identifies what is affected. In this case, it’s the air/fuel delivery system.)
01 – MAF (Mass Air Flow) Sensor Malfunction (The last two digits are a pair and they identify the specific location or sensor reporting the error.)

Urgency: Get this code fixed as soon as possible to avoid internal engine damage.

Diagnosis: Code P0101 is not dangerous to the driver and usually will not prevent the car from running. However, it will cause an increase in fuel consumption and a decrease in performance and efficiency. Continuing to drive the car with this error can lead to engine damage. The cost to repair the MAF sensor is minor compared to the cost of engine repairs if the check engine light is ignored.

The mass airflow or MAF sensor measures how much air is entering the engine. Check engine light code P0101 triggers when the amount of air flowing into the engine by the MAF sensor is outside of the manufacturer-specified range.

What Causes P0101 Error Codes?

Many things can cause your car to throw a code P0101; a dirty air filter or mass air flow sensor, to name a couple. Those are pretty easy to fix on your own and are usually right at the top of the engine so they are easy to access. More involved issues, such as a vacuum leak or a clogged catalytic converter are a little more complicated to correct. Here’s a list of the most common causes:

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

What are Some Symptoms of Mass Airflow Issues - P0101 Error Code

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

How to Diagnose Code P0101

With a mass air flow sensor error code, the first thing we need to do is get it diagnosed. Let’s discuss ways to figure out what is causing MAF error code P0101. 

Cost to Fix Code P0101

Now that we know what can cause a P0101 MAF error code, let’s take a look at the potential costs of the most common issues. Of course, you don’t want to rely on these numbers for exact pricing but it is based on national averages. Location, type of vehicle, and hourly labor rate will be the greatest factors in determining the price range.

  • Engine Air filter (parts and labor): $40.00 - $75.00
    • Standard air filter cost (parts only): $10.00 - $30.00
  • Mass airflow sensor (parts and labor): $200.00 - $335.00
    • MAF Sensor (parts only): $80.00 - $140:00
  • Catalytic converter (parts and labor): $1850.00 - $2020.00
    • Catalytic converter (parts only): $500.00 - $850.00

DIY Steps to Diagnose Code P0101

Since we know that the engine code P0101 can be caused by a dirty air filter, faulty mass air flow sensor, clogged catalytic converter, and more, let’s walk through some diagnostic steps.

Tools Needed:

Follow these steps to diagnose the potential causes of our P0101 MAF error code. It may be possible to fix and clear this error without buying any parts. Most OBD2 scanners give you the ability to clear the code causing the check engine light. After you attempt each fix, try clearing the code and driving the vehicle to see if it comes back on. It may not come back on right away so be patient.

STEP 1: Is the Air Filter Clean and Installed Properly?

Let’s locate the air filter housing that’s connected between your air intake and your throttle body or carburetor. Now, open that air filter box. Some require screwdrivers or socket wrenches and some just have clips keeping it closed. You will find that most air intakes disassemble easily. Inspect the air filter for dirt or grime that could be blocking airflow. If you hold it up and see light through it, it’s probably ok. SOME air filters and be cleaned and reused. If yours can’t be cleaned, consider buying a performance air filter that can be rinsed. It will save you money in the future.

Now, that the air filter is clean or new, make sure that it is installed and seated properly. Air filters should be fit in place. Reseat the air filter within the filter box if it is placed properly. This may fix your P0101 code but let’s complete step 2 as well. It is not difficult or expensive and may improve performance. 

STEP 2: Clean the MAF Sensor with Mass Airflow Sensor Cleaner.

Disconnect the wiring harness from the MAF or mass air flow sensor. Be careful and look for snaps or clips that hold it in place. Over time and due to their proximity to heat from the engine, that plastic gets VERY brittle and easy to break. Now remove the air intake hose from the air intake box. You should be able to see the MAF sensor inside the tube. Using mass airflow sensor cleaner, spray each side of the mass airflow sensor in 5-second intervals, waiting 10-15 seconds between sprays.

Important Notes: The MAF sensor wires are very fragile and break easily. Because of this fact, you should only use MAF sensor cleaner for this task and let it air dry. Never try to wipe the excess off or you will be buying a new MAF sensor. Mass airflow sensor cleaner dries very quickly. Reconnect the air intake tube, close the air intake box, and carefully reconnect the MAF sensor harness. You should hear a click from the plastic snap when you plug it in. That tells you that’s secure.

STEP 3: Do you have vacuum leaks?

Inspect the air intake system for vacuum leaks if the P0101 check engine code comes back on.

STEP 4: Maybe the exhaust is clogged.

So you have a clean MAF sensor and couldn’t detect a vacuum leak but that check engine light came back on. It’s probably an issue with the airflow through your exhaust. Maybe it’s a clogged catalytic converter or actual damage to the exhaust from road debris. A damaged exhaust with a kink in the line can prevent exhaust from flowing through the engine properly.

Don’t just buy a new MAF Sensor

Buying and installing a new mass air flow sensor without completing the entire diagnostic process may be a waste of money. Remember that sensors report that something is wrong with your car. Though sensors can go bad, it’s best to make sure that the issue isn’t with the vehicle first.

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