The manifold absolute pressure (MAP) sensor measures the air pressure in the intake manifold for the computer to adjust the air/fuel ratio. When a MAP sensor fails, it can affect engine performance or turn on the check engine light for code P0107B. This article explains how to test a MAP sensor with an advanced scan tool and a multimeter or voltmeter if you suspect the sensor is defective.

Lack of Power and Poor Fuel Economy Are a Couple Symptoms of a Bad MAP Sensor

How to Test the MAP Sensor with a Scan Tool

How to Diagnose the MAP Sensor with a Scanner

Check the Sitting MAP Sensor Reading
Turn the vehicle on without starting and with an advanced scan tool check the MAP sensor reading. Some vehicles have a barometric pressure sensor, which is the same type of sensor. It measures the barometric pressure in the air, and this reading will change with the altitude. The two readings should be equal or about the same.
Check the Working MAP Sensor Reading
Start the vehicle and see if the MAP sensor takes a reading and changes when you press the throttle. It should rise quickly when the gas is pressed, fall to a low number when the gas is released, and stabilize at a higher reading shortly after.
Graph the MAP Sensor Reading

Graph the sensor with an advanced scan tool. If the are spikes in the reading like in the picture below, the sensor is working intermittently and needs to be replaced.
Replace the Bad MAP Sensor
A bad MAP sensor will draw a low reading compared to the barometric pressure sensor reading and will have an inaccurate or no reading with the vehicle on. If this happens, the MAP sensor needs a replacement

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How to Test the MAP Sensor with a Multimeter or Voltmeter

The MAP sensor is usually attached to the air intake.

Probing the electrical connector's outside terminal for 5 volts — Probing the electrical connector’s outside terminal for 5 volts

Steps for Testing the MAP Sensor Electrical Connector

Disconnect the electrical connector
Look for corrosion in the connector’s terminals
Test the connector with a voltmeter
Place a lead on the electrical ground and lightly probe the outside terminal for 5 volts
Place a lead on the ground terminal (the opposing outside terminal) and test the outside terminal for 5 volts to confirm the computer is grounding properly

How to Test the MAP Sensor Electrical Connector with a Jumper Harness and Scan Tool

Step 1. Make a Jumper Harness with a Fuse

Make a jumper harness with a fuse and spliced wire ends.

Step 2. Place the Spliced Wire Ends to the Electrical Connector’s Terminal and Read for 5 Volts

Placing spliced wire ends to the outside and center terminal

Lightly press the spliced ends to the outside terminal (5 volts) and the center terminal.

MAP Sensor reading for 5 volts on a scan tool

Confirm with a scan tool that the connector is sending 5 volts down the signal wire.

If the terminal is getting electricity like in the exercise above, the MAP sensor is faulty and needs to be replaced.

Replace the MAP Sensor Yourself

Replacing the MAP sensor is usually a simple repair a novice can do. If you have tested the MAP sensor and know it’s defective, replace it yourself with videos at 1aauto.com

How to Test a MAP Sensor