What Happens If You Disconnect Mass Air Flow Sensor?

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What Happens If You Disconnect Mass Air Flow Sensor?

The mass airflow sensor is a key sensor in your car. Your car has a lot of sensors, and this is just one that helps your car run properly.

That brings up the question of can your car run without the mass air flow sensor?

In this article, we will look at what happens when you disconnect the mass airflow sensor. Read on to find out all you need to know about when you unplug your mass airflow sensor and if your car will stay running or not?

What Happens If You Disconnect Mass Air Flow Sensor?
What Happens If You Disconnect Mass Air Flow Sensor?

What does Mass Air Flow Sensor do?

Before going into detail on what will happen when you disconnect the mass airflow sensor it is important to understand what it actually does. If you want a technical definition of how a mass airflow sensor works, then you can take a look at the article we have here, but for this article, we will just cover the basic function of the mass airflow sensor.

The basic purpose of the mass airflow sensor is to measure the amount of air that is going into the engine so your car can release the proper amount of gas into the engine, so the car is able to run correctly.

What Happens If You Disconnect Mass Air Flow Sensor?

So, since the mass airflow sensor is used to measure air intake into the engine to keep the car running correctly, then what will happen if you unplug the sensor? Will the car die or stop running?

Well, the answer to that is no. If you disconnect the mass airflow sensor, then the car should keep running and still be able to start normally.

This is because the computer in the car if it does not receive a reading from the mass airflow sensor, will estimate and supply a number that it thinks it is supposed to have. This means that if your mass airflow sensor dies completely, then your car will stay running and surprisingly the car might run better without the mass airflow sensor. That is because if the sensor is bad or giving a wrong reading, then the cars guess might be closer to the actual amount of air that the engine is getting giving you a more accurate fuel mixture.

Why disconnect the mass airflow sensor?

So, why might you want to disconnect the mass airflow sensor and drive around like that?

Well, the main reason is to test the mass airflow sensor and see if it is working right.

Like has been mentioned by driving without it you might get better gas mileage and if that is the case, then it is a sign that you should clean or replace your mass airflow sensor because it is giving false readings.

On top of testing the mass airflow sensor by disconnecting it, you can also test some of your vehicles other sensors by disconnecting the mass airflow sensor.

If the car dies when you disconnect the mass airflow sensor, then that means it was working right and that your computer has issues. It isn’t able to use the tables programmed in it to guess the amount of fuel needed. Also, if the computer isn’t the issue, then it means one of the other sensors is probably off if the car isn’t able to keep running without the mass airflow sensor because the sensor was helping the car compensate for the other issues that it was having. So as you can see disconnecting the mass airflow sensor is actually a good way to test a variety of things.

Another way to test your MAF is using best obd2 scanner, it will find the error in your Mass Air Flow Sensor.

When should you disconnect the mass airflow sensor?

So, now that you know the reasons for unplugging the mass airflow sensor, the next question is when you should do it?

Well, the answer to that is pretty easy. Whenever your car is running rough, backfiring, or seeming to have issues with the fuel mixture, it is a good idea to unplug the mass airflow sensor. You can drive your car a bit and see if it runs correctly with the sensor disconnected.

If it does, then you know it was that sensor. If it doesn’t, then you know you need to look at one of the other sensors.

If it was the mass airflow sensor that is working improperly, then the first thing you should do to it is to clean it.

We have a guide here on how to clean it, but cleaning your mass airflow sensor is really easy and can help it start working correctly.If cleaning the mass airflow sensor does not fix the issues that it was having, then it is time to replace it. Sometimes mass airflow sensors get shorted or stop working and need to be replaced.

Once you have driven your car enough to test the mass airflow sensor it is a good idea to plug it back in or replace it after you are done testing. This is because it will help you get the best gas mileage possible.

That is because even though your car can run without the mass airflow sensor, you shouldn’t do it for long periods. That is because the numbers the computer generates are for brand new engines, and conditions change with the engine as it ages. By letting the mass airflow sensor make the readings, it allows for the most accurate numbers if it is working properly.

Conclusion

So, now you know what happens when you disconnect the mass airflow sensor. You know that your car will start and keep running even with the mass airflow sensor unplugged. In some cases, the vehicle might run even better if the mass airflow sensor is bad. On top of knowing what happens though when you disconnect it, you also know why you might want to disconnect it and also when to disconnect it. You know unplugging your mass airflow sensor is a good way to test it and other sensors, but you also know that driving a bunch with it unplugged isn’t good because it gives more accurate readings than just your computer guessing at the airflow. Now you know all you need to know about what will happen when you remove your mass airflow sensor from your vehicle.

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Mike Cross
Mike Cross
You have to look for teachers. If you want to be a mechanic, go hang out with mechanics.

15 thoughts on “What Happens If You Disconnect Mass Air Flow Sensor?”

  1. Good day,
    I found your article very interesting and helpful, but, i have a question for you. My MAF sensor went out on a 2000 Buick Regal, and i replaced the MAF sensor, it was still acting as though it was not working and the service engine light still came on, and the obd still said it was the MAF sensor. So i bought another MAF sensor, and needless to say, it is still acting like it is bad too, the car hesitates etc. do you have any suggestions as to what could be going on?

    1. Check your coils one at a time of course. disconnect plug wire from spark plug see if the spark is blue.If yellow replace the bad ones they are weak. If all good check injectors, fuel pressure etc. You can also check the throttle body see if the port from the pcv is plugged. IAC if only at idle. Then check pick you part and see if they will buy it. Lol

    2. If you replace the mass airflow sensor and it’s still running rough then check the MAP sensor. GM usually has both..

  2. Hello, I bought a ALAVENTE cool air intake for my 2014 Mazda 3 sedan. It does not have port to plug the MAF sensor in. What do I do about that? Do I need to buy a MOD so I can plug it in or do I need to completely unplug the MAF sensor from the engine compartment and let the O2 sensor decide the amount of fuel to air ratio?

  3. Hi there I have a HYUNDI Santa Fe 2004 2.7 it cuts out while driving at random. I have replaced crank sensor and air control actuator and a fuel pump , it still stop at random no codes come up at all and now the engine hunts at 3000 rpm not sure where to go from here , good spark , Injector’s have pulse,good fuel pressure

    1. I have an 06 Honda Accord ex and the fans don’t turn on. But if I turn the AC on they work. Also changed the coolant temp sensor and checked relays. But the fans still don’t turn on.

      1. The fans don’t run continuously they kick on and off but if there not doing that then there is a lil box that plugs into the fan shroud area ,it looks kind of like like a lil square crate cage and inside you’ll see something similar to air conditioning coils this box has 2 wires that come off and plug into a harness powering the system . Those wires for some reason has a tendency to melt and in fact they sell a lil kit just for that with the harness made on you just need to solder it up wrap it and plug the box in that’s what I found on mine

  4. Also when you turn off the ignition the idle air speed actuator is buzzing for a few seconds, I unplugged it while the motor was running the engine stopped and now will not start, put the old actuator back on and it still will not start , before I unplugged the new actuator the rpm went from normal it jumped up to 2500 rpm and stayed there unless you unplug the air speed actuator something is shorting maybe now sure , thank you

  5. I just noticed After the buzzing noise stops from the air speed actuator when ignition turned off there is a click noise from the under hood fuse box seems like some sort of electrical problem , I have gone through my car an check and cleaned all earth straps front to rear of car , hope you can help me with this ongoing problem, thank you

    1. Hi Petar.
      First, the Idle Air Control is a motor that the computer uses to increase or decrease the engine idle speed. The ECU has a table that tells it the target idle speed and compares the actual idle speed with the table to know which way to run the idle motor.
      When the car is started the ECU wont know where the idle air control motor is. So when the car is switched off, the idle motor is “reset” to a home position. That’s the buzzing sound you are hearing. On most cars the engine has to have been running before the idle control will reset. I think the click you hear is a relay turning the power off from the idle motor.
      The running at 2500 RPM might be that once the idle motor was unplugged, the ECU has to “re-learn” the correct idle speed so it will run at maximum idle speed until that process is complete. It should only run at high idle for a few minutes or less though. Double check you have plugged everything back in correctly.

  6. 98 mustang 3.8 Hard start in morning local firestone said 1010:00 for fuel pump. I decided to clean M A F ! It’s a bit better , starts faster after setting now! Should I just replace! Car runs very good over all

  7. Nice article. I do it and on my W211 220CDI which smoke, vibrate at stop, loud sound (since unplug EGR)… I unplug the MAF and plug the EGR, every thing going well. I ask : to unplag for ever,- is there any problem on the ECU?

  8. Hi There
    I have a BMW 650i V8 and wish to install a Cone Type Sports filter (Similar to a K&N Reusable Filter) which installs neatly straight onto the Throttle Body, now i can install the MAP Sensor somewhere on the New Sports Filter, by cutting a slot and installing the MAP Sensor, or i can leave it off, having read the above, what would your option be and why?, thank you, Montana

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