7 Warning Signs Of A Bad Mass Air Flow Sensor

Mass Air Flow Sensor Symptoms

One of the key components of an electronic fuel injection system of the vehicle is the mass air flow (MAF) sensor. A mass air flow sensor, or MAF, is an important part of a car’s engine management system. It measures the amount of air flowing into the engine so that the engine can be supplied with the correct amount of fuel. If the MAF sensor is not working properly, it can cause a number of problems with a car’s engine.

Most modern cars contain the intake air temperature sensor built into the mass air flow sensor. This ensures the optimum amount of air is fed into the combustion chamber and the vehicle utilizes the complete fuel, hence no fuel is wasted.

Here, in this article, we are going to discuss the seven symptoms of a bad mass air flow sensor.

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Signs Of A Bad Mass Air Flow Sensor

Mass Air Flow Sensor With Dust Cleaner
Mass Air Flow Sensor With Dust Cleaner

As the mass air flow (MAF) sensor has all the air that is to be fed into the intake manifold of the engine, there is a lot of air passing through it. The amount of air passing through it is around 9000 liters for every liter of fuel injected.

This much air poses a threat to the contamination of the mass airflow sensor and causes the failure of the mass airflow sensor. This sensor failure can happen as early as 18,000 miles, but this estimate is different for compact and large vehicles.

If your mass airflow sensor is not working properly it can cause some major problems in your vehicle such as low compression or low vacuum. Hence, it is necessary to check for the health of your vehicle’s mass airflow sensor.

You can know if your mass airflow sensor is failing by looking out for the common symptoms listed below:

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7 Wild Symptoms Of A Bad Mass Air Flow Sensor

  1. Check Engine Light
  2. Hard Starting
  3. Rough Idling
  4. Engine Stalling
  5. Hesitation
  6. Lean Mixture
  7. Rich Mixture

1. Check Engine Light

Engine Check Light
Engine Check Light

Engine check light appears when the car has an electrical issue related to ECU. A bad mass air flow causes to illuminate a check engine light. A check engine light can also appear when there is a wiring issue, a loose connector, or a cut in the wiring.

2. Hard Starting

Car Not Starting
Car Not Starting

Hard starting is also a sign of bad mass air flow. A bad mass air flow sensor will not provide correct data to the ECU and the ECU will not know how much fuel to inject into the engine cylinder to start the car.

Because starting the car requires high fuel compared to standing idle, which makes the car difficult to start.

3. Rough Idling

Tachometer Showing An Idling Engine
Tachometer Showing An Idling Engine

Rough idling is also a symptom of bad mass air flow. A bad mass air flow sensor causes a rough idling. It will not send data in a timely and the ECU does not know how much fuel to inject.

Hence, the engine of the car will have a rough idle. It also forces the car to jerk and vibrate rapidly when it is stationary.

4. Engine Stalling

Beautiful Girl Is Starting The Car
Beautiful Girl Is Starting The Car

Engine stalling is also a sign of a bad mass air flow sensor. A bad mass air flow sensor forces the engine to stall. It does not send the input to the ECU or sends the incorrect input to the ECU.

Therefore, the ECU does not know how much fuel to inject into the cylinder, and the car stalls shortly after starting.

5. Hesitation

Engine
Engine

Hesitation or jerking while driving is also a sign of a bad mass air flow sensor. When you accelerate the car and it shows hesitation, such as missing at instances and not accelerating smoothly, can be a sign of a bad mass air flow sensor.

It can also change the acceleration of the car without the input of the driver.

6. Lean Mixture

Automobile Combustion Chamber
Automobile Combustion Chamber

A lean mixture can also be a symptom of a bad mass air flow sensor. A lean mixture means the fuel ratio is lower in the air-to-fuel ratio.

A bad mass air flow sensor sends wrong data to the ECU, which sometimes leads to a lean mixture. A lean mixture makes the engine quite difficult to start because of the low amount of fuel.

7. Rich Mixture

Engine Piston
Engine Piston

A rich mixture can be an indication of a MAF sensor symptom. A rich mixture means that the fuel ratio is higher compared to the air.

A bad mass air flow can allow too much fuel into the engine, which increases your car’s fuel consumption and also reduces the car mileage.

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FAQs

Will my car run if I unplug the MAF sensor?

The answer to this question is not entirely straightforward. If you unplug the MAF sensor, the engine will still start, but it will not run as efficiently. The MAF sensor measures the amount of air flowing into the engine, and if it is not working properly, the engine will not be able to adjust the fuel mixture accordingly. This can lead to decreased fuel economy and increased emissions.

Will a bad MAF sensor throw a code?

A bad MAF sensor can cause the engine to run lean, which can trigger a check engine light. The code will typically be P0171 or P0174.

How do you know if your mass airflow sensor is bad?

There are several signs that indicate a faulty mass airflow sensor. These include the engine being hard to start or turn over, stalling shortly after starting, hesitating or dragging while under load or idle, hesitation and jerking during acceleration, and running excessively rich or lean. Additionally, your engine may start regularly misfire and the check engine light may be lit. You may also notice your car stuttering and sputtering while idling or even while driving along. Finally, the engine may not even start when the key is turned in the ignition.

How do you test a mass airflow sensor?

The most common way to test the mass air flow (MAF) sensor on all Ford, Lincoln, and Mercury cars and trucks is by starting the car and connecting a diagnostic tool. Then, gently tap the MAF sensor, and if the engine stumbles or changes speed then the sensor may need to be replaced. Alternatively, you can use a variable airflow and a test signal to measure the output voltage from the MAF sensor. Additionally, you can use a scope to connect to the MAF sensor signal wire and snap the throttle wide open as fast as possible to check for any irregularities. Once tested, let the MAF sensor dry in the air before refitting it into the air box and taking your car out for a test drive. Below is a detailed guide on how to test a MAF sensor.

Related Poster• How To Test Mass AirFlow (MAF) Sensor With/Without Multimeter


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