FAQ – What is the MAP Sensor?

FAQ – What is the MAP Sensor?


Today we’ll be covering the Manifold Absolute Pressure Sensor (MAP) in our EFI Guide to answer the common question “What is the MAP Sensor?” Many times customers ask what this sensor is, where it’s located and what it does exactly. Common problems that arise from OBDII related trouble codes can often lead to replacement of the pressure sensor or troubleshooting the sensor itself.


Today we’ll go over what the Manifold Absolute Pressure sensor is and what it’s role is in your vehicle’s EFI system. We’ll also be sharing a few of our more common MAP sensor How Tos and DIY articles at the bottom of our What is the MAP sensor Guide.

What is the MAP Sensor?


This sensor or the Manifold Absolute Pressure Sensor can often be called the pressure or vacuum sensor for short. This sensor is found on vehicles that operate a speed density as well as a Karman or Vortex style Air flow equipped vehicles as well.

The sensor is a basic pressure sensing unit that detects and measures intake air volume. It measures the air intake volume by being connected to the intake manifold. By monitoring changes to the intake manifold pressures, it can accurately inform the ECU or PCM of what is entering the engine.

What is the MAP sensor comprised of?



Usually a three pin sensor, the MAP unit consists of a piezoresistive silicon chip and an Integrated Circuit (IC). During the manufacture process, vacuum is applied to one side of the silicon chip and manifold pressure applied to the other side. This creates a silicon deflection dish of sorts that can measure the incoming air charge.

A GM GEN III MAP Sensor Diagram

When pressure in the intake manifold changes, the silicon chip flexes, causing a change in its resistance. The varying resistance of the sensor causes a change in signal voltage at the PIM (Pressure Intake Manifold) terminal.

How Do I test the MAP Sensor?


Because the MAP is typically made up of three wires, you won’t have a hard time distinguishing what is power, ground and signal. Shown below is a typical MAP wiring, and in this particular example we’ll be illustrating the MAP sensor wiring pinout for the 2JZGTE.


The sensor and ECU are wired as shown in the diagram. As manifold pressure increases  (approaches atmospheric pressure) there is a proportionate increase in PIM signal voltage.

There’s a few ways to test your MAP sensor to see if it’s any good or need replacing. You can measure the voltage being sent by the MAP sensor by applying vacuum and pressure and reading the PIM or MAP signal wire.

You can also measure the resistance between the positive and low reference wires to see if the MAP sensor is still within operating specifications. To check out more of our How to Test a MAP sensor guides, click the links below for just a few of our more popular MAP sensor testing articles.

Have any questions or comments about our What is the Manifold Absolute Pressure Sensor article? Leave them for us below!