Mass air flow sensors

Air flow into the engine is essential for efficient combustion, which is where the mass air flow sensor comes in.

How MAF sensors work

Types and characteristics

Installation and fault finding

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Mass air flow sensors

How MAF sensors work

The most common type of mass air flow (MAF) sensor is located inside the intake air duct between the air filter and the throttle body. Also known as the plug-in hot wire type, it consists of a heating resistor, an intake air temperature measurement resistor, an intake air temperature sensor and a control circuit.

To measure the volume of air entering the engine, some of the intake air from the air cleaner is bypassed into the hot-wire measurement area, where the volume of air intake is measured. This measurement is converted to a proportional voltage in the control circuit before being sent back to the ECU to calculate the amount of engine intake air volume.

At the same time, the intake air temperature sensor takes a measurement and sends it to the ECU to tell it how hot or cold the air is. The ECU can then judge the air density and correct the quantity of fuel injection.

Features and benefits

Integrated, compact design that minimizes air pressure drop.
Reduced contamination of the sensing element, increasing reliability.
More accurate airflow detection.
Small size passage structure that is easy to install.

Small, lightweight design
A world first, DENSO’s plug-in type MAF sensors are inserted into the air-intake wall, reducing weight, size and installation time, with no impact on performance.
Better accuracy
The unique bypass passage design prevents air from turning towards the sensing element and reduces air pulsations, allowing for a more accurate measurement and protecting the sensor from contaminants.
Simple installation
Simply insert the part into the sensing element and the air flow meter can be used, making it versatile and usable in a wide variety of air systems.

Types and characteristics

By creating an innovative, market leading design, our MAF sensors set the standard for efficiency and accuracy, enabling improved engine performance.

Mass air flow sensors types

Plug-in hot wire

Now the most common type of MAF sensor, our product has a bypass passage design that increases efficiency, accuracy and is easy to install.

Characteristics

Smaller than competitor’s products and with a unique design that increases both accuracy and reliability, you can depend on DENSO’s MAF sensors for high performance every time.

Installation and fault finding

Although DENSO’s design makes our MAF sensors easier to install and more reliable, there are still many questions that are frequently asked about the product.

Installation

Ensure maximum efficiency by installing your MAF sensor correctly.

Disconnect the MAF sensor connector. Remove the screws and plug-in type MAF Sensor. If MAF sensor has a suction pipe, loosen the pipe clamps that locate the MAF sensor into the air intake duct and remove the MAF Sensor
Install the new MAF sensor with the screws into the air intake duct and connect the MAF connector. If the MAF sensor has a suction pipe, tighten all pipe clamps. Turn the engine on and check if the intake system works properly
Check the entire air intake system for leaks and make sure the o-ring is not cracked or jammed when installing it

Fault finding

Find any MAF sensor faults quickly and fix them easily.

MAF sensor contamination or damage is usually caused by an air filter that is in poor condition or incorrectly installed. A damaged or contaminated MAF sensor can still function, but the changes to its characteristics can cause a wide variety of driving problems.

Poor startup: First combustion occurs, but combustion is incomplete.
Instability at idling: High idle speed, low idle speed or unstable idle.
Poor drivability: Hesitation during acceleration, engine backfires, abnormal knocking or black smoke emitted.
Stalling: Shortly after startup, when accelerator is depressed or released.

A problem with the MAF sensor can cause the engine warning light to turn on. This fault is stored as a diagnostic trouble code (DTC) in the engine ECU and can be inspected by a DTC scan tool. However, if the root cause of failure is a clogged MAF sensor passage, the engine will usually start, will run poorly or stall, and may not set a DTC. If the MAF sensor is defective, it will need to be replaced. This is a simple process. If the MAF sensor is contaminated, cleaning it may provide a temporary solution, but this may damage the sensor’s delicate hardware. If the MAF sensor is replaced, make sure the air filter is also installed properly.