How to Test a MAF Sensor

Test MAF Sensor

The mass air flow (MAF) sensor reads the air flow entering the engine. A defective MAF sensor can cause engine stalling, a rough running engine, and a check engine light for trouble codes like code P0171. Find out how to test a MAF sensor and how to replace a defective one with these tips from our mechanics.

Symptoms of a Bad or Faulty MAF Sensor

  • Rough running engine
  • Stalling engine
  • Check engine light for MAF code

Steps to Take Before Testing the MAF Sensor

Look Under the Hood for Obvious Causes

If the engine is running rough or stalling out, check underneath the hood for obvious, loosely disconnected parts that may be the cause. Check for disconnected wires, hoses, and air intake tubes.

Check the Oil Condition and Level

Engine oil at full level and in good condition
Engine oil at full level and in good condition

Steps for Checking the Oil Level and Condition

  1. Remove the dipstick
  2. Clean off the dipstick
  3. Reinsert and remove the dipstick
  4. Confirm oil is between the two hashmarks
  5. Check the condition of the oil—it should look clean

Inspect the Air Intake and Engine Air Filter

Inspect the electrical connector’s terminals for discoloring or damage. Remove the air filter housing cover and check the condition of the engine air filter. Make sure it is clean, and clean the air box if needed since that can affect air flow.

Physically Inspect the MAF Sensor

Common part of the sensor to find debris that can affect readings
Common to find debris on wire of MAF sensor that can affect readings

Remove and check the MAF sensor for debris like dirt or leaves. These are sometimes found on the wire in the MAF sensor.

Consider Cleaning the MAF Sensor

Try cleaning the sensor with MAF sensor cleaner. Follow the directions listed for the particular cleaner.

How to Test a MAF Sensor with an Advanced Scanner

Stream a MAF Sensor Reading

Reading of a bad MAF sensor at idle
Reading of a bad MAF sensor at idle

You can get a reading of the MAF sensor with an advanced scan tool.

Connect to the vehicle’s computer and stream the MAF grams per second (GPS) reading. The reading should be fairly consistent and not drastically fluctuate, and should read higher at higher RPMs. Normal GPS ranges will vary depending on the engine size. Larger engines will have higher readings.

Test the MAF Sensor Reading

Wiggling a MAF sensor electrical connector

Wiggle the electrical connector and the wires and see if that causes a spike, which indicates the MAF sensor is faulty.

Replace the MAF Sensor and Watch the Reading

Reading of a good MAF sensor at idle

Replace the MAF sensor if it is faulty. Take another reading, and check if the sensor is working correctly and if replacing the MAF sensor improved engine performance.

Replace the MAF Sensor Yourself

Check out 1A Auto’s how-to videos and learn how to replace a faulty or dirty MAF sensor yourself with repair videos for many makes and models.

Common Steps for Replacing a MAF Sensor

  1. Disconnect the Electrical Connector

    Press the tab and disconnect the connector from the MAF sensor

  2. Remove the Screws

    Loosen and remove the screws from the MAF sensor

  3. Remove the MAF Sensor

    Remove the MAF Sensor

  4. Install the New MAF Sensor

    Insert the MAF sensor into place

  5. Tighten the MAF Sensor

    Tighten the screws to the new MAF sensor

  6. Connect the Electrical Connector

    Connect the electrical connector to the MAF sensor

Shop Related Parts

Fix a faulty MAF sensor yourself with quality auto parts at 1aauto.com

Related Content

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How to Test a MAF Sensor | Expert Tips to Diagnose and Fix
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How to Test a MAF Sensor | Expert Tips to Diagnose and Fix
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The mass airflow (MAF) sensor reads the airflow entering the engine. A defective MAF sensor can cause engine stalling, a rough running engine, and a check engine light for trouble codes like code P0171. Find out how to test a MAF sensor and how to replace a defective one with these tips from our mechanics.
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1A Auto
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