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Detailed Guide: What Does A Map Sensor Do?

You must have heard the term, Map sensor sometimes at the mechanic’s shop. Perhaps, even during the time when your car salesperson is describing the various features of a vehicle. Have you ever wondered what a map sensor does exactly? Let us first understand that.

MAP sensor stands for the words – Manifold Absolute Pressure sensor and serves the function of detecting or measuring an internal combustion engine’s electronic control system. They provide manifold pressure data to the engine’s electronic control unit (ECU).

Importance of Map Sensors

While we have a basic understanding of what a map sensor does, here is why it is most important:

  • Most modern generation vehicles work on MAP sensors. The reason is simple. A MAP sensor helps generate efficient fuel consumption. Many vehicles have bad MAP sensors, which can lead to poor overall performance. Thus, it becomes important for one to keep a check on the engine and the sensor.
  • To detect a faulty MAP sensor, one is required to perform an engine diagnostic. This will give you an estimate of whether it is time for you to replace the MAP sensor.
  • A MAP sensor is located on the intake manifold of a car’s engine. They are primarily installed in a place wherein they can provide instant manifold pressure to the engine’s ECU. There are some that make use of MAP that gives a result of optimum combustion, whereas others make use of MAF or mass airflow sensors.

How Does a Map Sensor Work?

When the engine of a vehicle is not running, the pressure of the intake manifold is the same as the exterior barometric pressure. However, as soon as the engine starts, a vacuum is generated, and there is more pressure around the intake manifold.

The vacuum inside an engine ranges from situation to situation. It can range from 0 to 22 inches or more. It depends on the operating condition of the car. It may be at sea level or above sea level, like a mountain where more oxygen is required.

At the time of ignition, the powertrain control module (PCM) turns to the MAP sensor for data. The data is determined by the MAP sensor according to the atmospheric pressure, as mentioned previously.

MAP sensor

Photo Credit: https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-manifold-absolute-pressure-sensor-map-sensor

The following are the essential elements that MAP sensors consider before estimating the data:

  • Engine rpm
  • Throttle position
  • ​Coolant temperature
  • ​Air temperature
  • ​Oxygen sensor
  • EGR valve

Different Uses of Map Sensor

How can we figure out what a map sensor does exactly and what its actual uses are? Following given are some of its uses:

1. Determines Fuel Consumption


Numerous fuel-injected engines make use of different systems to determine how much fuel the engine has consumed. Among the many, MAP is one such sensor that facilitates sending signals of pressure directly to the engine’s computer.

It is after this that the computer manages to make use of the information to calculate the vehicle’s air mass flow rate and air density. These two components are significant in adding to the productive output of any given vehicle.

It is after this that the computer can predict how much fuel is required for the best combustion rate.

2. Determines Fuel Delivery

There are several factors that play a major role when it comes to determining your engine’s fuel delivery. Elements like the engine speed or RPM, air temperature, and air–to–fuel ratios all comprise an imperative part of this procedure.

The vehicle naturally accelerates faster when you provide it with abundant gas. Your desired speed, thereby, also depends on how fast your engine can run.

As you may be able to understand, the MAP sensor utilizes these elements in determining the accurate information. The amount of gas to be pumped into the cylinder essentially depends on the data provided by MAP.

3. Adjusting to the Changing Environment


You may require normal fuel bumping in a city. However, requirements change when the car is traveling let’s say, on a high mountain. The car consumes more fuel in such an environment. Thus, the air–to–fuel ratio obviously differs.

MAP sensors deliver the respective requirements. MAP sensors supply relevant information to the engine, and the driver is kept informed of the same.

4. To Tell the RPM Difference

MAP sensor’s values change with the change in the number of activities in the car. The MAP sensor will showcase a 60kPa with an RPM of 1800. However, if you turn the air conditioning on, there is a slight difference in the outcome.

MAP sensors are essential to send the proper signal to the computer.

5. MAP V/s. MAF Sensor

MAP sensor advantages

Photo Credit: http://my206xr.blogspot.in/2010/05/peugeot-206-map-sensor.html

Many times, experts face the difficult question of which type of sensor is better for an engine. While, Mass Air Flow sensor or MAF sensor are fueled directly by both, mass air flow and speed-density calculations; MAP sensors calculate the density of air by measuring the temperature first.

MAF sensors are easier to tune. However, MAP sensors require lesser restriction when it comes to intake tract. People have experienced consistency with MAF.

Understanding the Advantages and Disadvantages of Map Sensors

A. Advantages of Map Sensors

  • Driver experiences lesser restriction in the intake tract.
  • There is a lot more room regarding movement in the intake tract.
  • ​The engine can measure air consumption even at a higher horsepower.
  • ​It impacts the reliability of the engine in a positive way.
  • The driver can encounter error-free engine functionality.

B. Disadvantages of Map Sensors

  • At times, it can be quite a task to tune the engine with the MAP sensors.
  • The vehicle needs a good quality Volumetric Efficiency table for the MAP sensor to deliver productive results.
  • Slight complications arise when new modifications are implemented.


Now that you are aware of what a map sensor does exactly, make sure you invest substantial time into deciding the right type and model. We hope this information regarding Map sensors proves valuable to you. If you have any questions, do leave a comment.