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Symptoms of Bad MAF Sensors, Causes, Fixes, and Replacement Cost

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Feb 27 2024

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MAF (Mass Airflow) sensors are necessary components of the current-stage engines, which capture the amount of air being sucked into the engine. This data is critical for the engine control unit (ECU) to determine the correct air-fuel ratio for combustion, enabling the engine to work efficiently by consuming the least fuel amount possible. To provide complete guidance in this blog, you’ll learn the symptoms of bad MAF sensors, causes, fixes, and replacement costs. 

In most MAF sensors, the working part is represented by a heated wire or film connected to a temperature sensor and an electronic circuit. The air molecules are allowed to move in and out of the sensor, which cools down the heated wires or film. When cooled, there is a change in the electrical resistance. With the use of this change in resistance, the ECU is allowed to measure the mass airflow rate. This is then compared to pre-determined parameters in order to adjust the fuel delivery and ignition timing.


There are two main types of MAF sensors:

Hot Wire MAF Sensor

The film sensor style works with a thin wire or a film of determined temperatures but above that of the environment. The wire surface acts as a thermal emitter, which warms the air as it flows by, causing a decrease in its electrical resistance. Therefore, it can be understood that the ECU calculates the mass airflow rate by reading out the change in resistance.

Hot Film MAF Sensor

Hot MAF sensors are essentially just another type of hot wire sensor (but use a filament instead of a wire as the sensing element). The film is kept in a heated state, and any air moving over it instigates a change in resistance as the resistance drops. This is gauged through the reading of the ECU to determine the amount of air inflow.

MAF sensors significantly affect an engine's performance quality since they are so closely related to the fuel and combustion systems. Therefore, you need fuel system services if you are experiencing poor fuel efficiency.  An MAF sensor failure results in drivers getting into trouble when driving, including poor acceleration, uneven idle, and low fuel economy. CA sensors are an integral part of an engine's operation. Therefore, they must undergo routine maintenance and checkups to maintain the optimal engine performance level.

If the MAF sensor fails or is covered with dirt, debris, or wrong calibration, there is a risk of getting incorrect airflow readings to the ECU. Consequently, the result is incorrect fuel mixture and performance problems. When the sensor fails to work correctly in such cases, it may have to be cleaned or replaced to begin operation again.

Overall, MAF sensors are the units responsible for accurately measuring airflow and helping in the proper functioning of the combustion and performance relating to the fuel burned.

Symptoms of Bad MAF Sensors, Causes, Fixes, and Replacement Cost

Symptoms & Causes Of Bad MAF Sensors

Check Engine Light (CEL) Illumination

When the malfunction of the MAF sensor occurs, the check engine light comes on as one of the motor vehicle's diagnostic systems. The ECU sends the vehicle a warning light. That is a signal from the ECU to indicate that the vehicle has a system problem, which needs prioritization. The ECU is a hardware programming executor that monitors various sensors, the MAF sensor among others, to guarantee a normal engine operation. The ECU checks for irregular or wrong readings from the MAF sensor and flashes the CEL light to the driver, signaling the presence of an error.

Decreased Engine Performance

The functionality of the MAF sensor is critical to the engine's proper functioning. Any problem with it can generate poor engine performance, resulting in reduced power output, a longer time to gain speed, and general additional delay throughout the engine performance. For the correct air-fuel ratio for combustion, the MAF sensor is the main factor that utilizes the volume and density of the incoming air. The presence of a faulty MAF sensor may either lead to a decline in fuel-air mixture accuracy or the transmission of the wrong data altogether; hence, the engine will experience poorer performance. It may lead to a reduction in power while accelerating, for instance, while overtaking, on a motorway on-ramp, or hill climbing.

Symptoms of Bad MAF Sensors, Causes, Fixes, and Replacement Cost

Rough Idling or Stalling

Additionally, the engine might be in rough idle or stall at certain times for no apparent reason, which are the symptoms of a bad MAF sensor. At such times as the engine is idle, it needs to be very meticulous in managing the air-fuel mix in order to avoid rough and sudden changes.

On the contrary, if the MAF sensor is not functioning well while supplying inaccurate airflow readings to the ECU, the engine may sometimes maintain abnormal idle, surge, or fluctuate in idling speed. In worse-off conditions, the engine will inevitably fail to start or it might even cut out when the vehicle is at a stop-over or when the engine just starts to run.

Engine Misfires

When the working state of the MAF sensor is broken, the fresh atom-fuel mixture which the engine cylinders receive might have an incorrect ratio, subsequently causing misfire of the engine. Surging of engine is a phenomenon when the air-fuel mixture fails to burn and the piston in one or more cylinders isn't completing a full stroke and thus loss of power and harsh running.

Fixes of Bad MAF Sensors

Cleaning the MAF Sensor

Under certain conditions, an improper running of the MAF sensor can occur when there is dirt, dust or debris accumulated on the metal element. The MAF cleaning will use a specialized is an efficient approach that cleans contaminants and make the sensor to function again properly. A cleaner for the MAF sensor must be used that is designed to be used on a MAF sensor and instructions should be carefully read before using it so as not to damage the sensor.

Inspecting and Cleaning Air Filter

An accumulation of soot or dirt on the air filter may prevent the MAF sensor from getting air, resulting in faulty readings, and the sensor may break down. Periodically running the system and checking the air filter ( if needed can be done ) while replacing the air filter to improve the flow of clean air and MAF sensor problems. At periodic times, air filter maintenance is crucial for healthy and satisfactory engine performance and durability.

Replacement Cost of Bad MAF Sensors

The cost for a bad mass airflow sensor replacement can differ depending on numerous factors, such as the make and model of the vehicle and the price of a new mass airflow sensor, whether done at a dealership or through an independent mechanic or DIY.

Parts Cost

The price of the MAF sensor itself, which could be at the threshold of $50 to $400 and over, varies depending on the model of the car and the quality, as well as the brand of the sensor. OEM (original equipment manufacturer) and MAF (Mass airflow Sensors) are currently more expensive than aftermarket ones.

Get Your Car Fixed With Eric’s Car Care

If you are experiencing any of the symptoms mentioned above, there is a high chance that you need a replacement of the MAF sensor. To seek mechanic services, you can call us at 713-352-8058 to get your MAF sensor replaced.

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