Dan Ferrell writes around do-it-yourself auto maintenance and repair. He has actually certifications in automation and also control technology.

You are watching: How to test mass air flow sensor with multimeter


Symptoms the a bad Mass Air flow Sensor

Symptoms of a faulty massive air circulation (MAF) sensor might include:

poor fuel economyerratic performancehesitationhard startingno startingstalling when equipment engagedlow engine powerengine running in fail-safe modecheck engine light onpoor or unstable idleautomatic transmission shifting concerns (on part models)

What an MAF Sensor Does

The MAF sensor procedures the volume and density the the wait entering the engine. Some likewise measure the temperature that the waiting entering the engine. The computer uses this measurement, along with other inputs, to calculation the ideal air-fuel ratio and also spark timing according come engine operating conditions. On a auto with an automatic transmission, the MAF sensor may help with change timing together well.

Although there are two common species of MAF sensors, hot-wire and also hot-film, hot-wire species are the most common. Troubleshooting test measures for hot-wire sensors may vary native one vehicle make come the next. Friend can further divide MAF sensors into low-frequency, voltage, and high-frequency types.

Some automobile models use a MAF sensor that communicates v a voltage signal to the computer. But an ext recent models might use a voltage frequency signal.

What You need to Troubleshoot her MAF Sensor

Whatever your sensor type, general troubleshooting steps remain basically the same. A straightforward digital multimeter (DMM) with at least 10 Megohms that impedance (to defend circuits and also your car's computer) will help you test your MAF sensor. In part cases, though, you’ll require a DMM with a frequency scale, relying on the type of MAF sensor your vehicle uses.

Thus, it’s a an excellent idea to have the automobile repair hand-operated for your certain model to inspect the correct specifications and form of sensor your automobile is using. If you don’t have this manual, you have the right to buy one from Amazon. Haynes manuals come v step-by-step actions for numerous troubleshooting, replacement and maintenance projects you can do at home.

The adhering to are general trial and error procedures the can apply to most automobile models top top the road today.

Also, if the examine engine light is on, make sure to download trouble codes indigenous the computer's memory. The codes may give you the reservation to resolve the problem. If you don't have a scan tool, most auto components stores will certainly retrieve problem codes because that you.

Location that the MAF Sensor

Look for the MAF sensor between the waiting filter box and also the throttle body. On part models, the sensor is within the air filter housing.

If friend need help locating the sensor, above the automobile repair hands-on for your details vehicle make and also model.


1. A fast MAF Sensor Diagnostic Procedure there is no a DMM

2. Exactly how to test an MAF Sensor

Testing the MAF sensor’s power feed

Testing an MAF sensor’s voltage signal

Testing a MAF sensor’s frequency signal

Testing the MAF sensor’s hot wire

3. I replaced My bad MAF Sensor yet I check out No Improvement

4. What If mine MAF Sensor is Good


Look because that the MAF sensor in the waiting cleaner assembly.

Photo courtesy the Tennen-Gas top top Wikimedia.

1. A quick MAF Sensor Diagnostic Procedure without a DMM

Sometimes, it’s possible to do a fast diagnostic that the MAF sensor without the use of any type of test equipment, relying on the particular sensor fault. For example you can shot this when taking care of intermittent performance issues, a no-start condition or negative idle problems.

If your automobile has been suffering intermittent faults or poor idle problems:

Engage the parking brake.Set the transmission to Park (automatic) or Neutral (manual).Start the engine and also let the idle.Pop the hood open.

Lightly madness the MAF sensor and also electrical connector v a driver handle. Wiggle the wires together well.

If the engine stalls, idle is upset, or idle it s okay better, the MAF sensor is likely defective.

If the engine doesn’t start or idles poorly:

Pop the hood open.Unplug the MAF sensor electrical connector.Engage the parking brake.Set the infection to Park (automatic) or Neutral (manual).

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Try starting the enigne.