Test Maf Sensor Unplugged- Here’s What to Do


MAF or Mass Airflow Sensor is an important part of the electronics segment of any car engine. In case your MAF sensor gets into some trouble, you have no other way left instead of inspecting it right away. 

Now, is it possible to test MAF sensor unplugged? Or you have to do that in a plugged condition anyway? 

We are here to answer this particular question anyway. And this article will take you through a definitive guide on that. Let’s continue reading- 

What is A MAF?

MAF stands for Mass Air Flow, and MAF sensor is, as you know the mass airflow sensor that is in your car engine. Now the primary question is, what it is and how does it work? 

MAF sensor is one of the main electronic components of the fuel delivery system of a car engine. In simple words, it’s work is to report about the mass of the air coming into the engine. 

This information is delivered from the MAF sensor to the ECU(Electronic Controller Unit) of the engine. And ECU determines the amount of fuel needed to achieve a stoichiometric ratio of air and fuel. Usually, this ratio has to be different from time to time. 

Symptoms of A Bad MAF Sensor

Before troubleshooting, let’s be sure about whether we’ve got a bad MAF sensor or not. Usually, there are a few symptoms of a MAF sensor. Which includes- 

  1. A decrease in engine power. 
  2. The engine will stall or hesitate at acceleration. 
  3. Pood idling will take place along with a vibrating engine. 
  4. The engine will surge at idling. 
  5. A frequent stop at the gas stations will be taken p[lace. 
  6. You’ll have driveability problems. 

How to Test Maf Sensor Unplugged?

Right now, we are at the central part of the article, where we will be taking you through the process of test MAF sensor unplugged. Here go the steps- 

Step 1: Identify the location of the MAF Sensor

Open the hood of the vehicle, and locate the position of the MAF sensor. It will be in the air cleaner assembly, in case you haven’t done it before. To be more specific about the location of the MAF sensor, it’s between the throttle body and the filter housing. 

It will look like a cylindrical section or a block, and it will be a part of the air duct. In the case of some models, this will be inside the filter housing. 

Step 2: Locate the electrical connector

Now, as you have identified the location of the sensor, it’s time to look for the electrical connector on the air dust. It will help you to proceed with the next steps. 

In case you have any difficulties in locating the electrical connector, you can look into your car’s manual for some help. 

Step 3: Test the MAF Sensor

Now, it’s the main step where we will test the MAF sensor anyway. For that, you need to have the electrical connectors(that you have identified in the previous step) plugged into the power. Therefore, give it a check whether you can black probe the wires of the sensor. In case you can not back probe the wires, you can just use a piercing tool like a pin. Keep them like this while conducting the test. 

Now, if you use the second method, you need to wrap up the wires with electrical tape. And this is supposed to be done when you are done with the tests. This will, eventually, prevent any kind of trust buildup in creeping into the wires. 

However, the steps for conducting the test are several. Here, we are going with the most common two of them- 

Conducting the MAF Circuit Power Test

This is kind of a preliminary test as long as MAF sensor tests are concerned. Here are the steps- 

  1. Unplug the electric connector of MAF sensor. 
  2. Visually inspect the connector and look for a speck of dirt or damage. If found, take proper action to clean it at dry state. 
  3. Pull out the wires and check for any tightness. There also can be some dirt or burnt or even loosen up wire. 
  4. Now, set your digital meter into 20V or any closely values to it. 
  5. Connect the digital meter to the red probe of the connector power terminal. And connect the black probe of the meter onto the ground. In case you don’t get to the ground, this can also be the unpainted bracket, an engine block and even the negative terminal of a battery. 
  6. Now, turn on the ignition. But don’t start the engine. 
  7. Check out the digital meter reading. It should be somewhere between 14 and 10 volts. In case the reading is not within the expected range, there might be some fault in the circuit between the car computer and electrical connector. 
  8. Now, connect the probes black to the ground and the red probe to the battery positive side. It will give a reading between 10 to 13 over again. And this will be close to the battery voltage. In case the reading is not okay, there are some problems in the mass airflow filter which you need to fix anyway. 

Step 4: Identification

Once you are done with the previous steps, identify the power, grounds, and wires that carry signals. In case you don’t know the information exactly, you might need to ask the manufacturer or an automotive technical for that help. 

Step 5: Put It Back in Its Place

Once you are done with the testing, you need to either fix any problems that are in the mass airflow sensor. In case the damage is at a critical condition, it’s better and suggested to put a new MAF sensor in the place of the old one. 

Bottom Line

In case you want to test the MAF sensor unplugged, this will be your go-to guide. Apart from the regular testing, you can conduct a MAS sensing element testing for continuity, MAF sensor voltage signals and so on. Good luck! 


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