In this tutorial, I'm going to explain how to test the manifold absolute pressure (MAP) sensor.
Testing the manifold absolute pressure (MAP) sensor simply involves checking its voltage signal with a multimeter while vacuum is being applied to it.
This is a very simple test that will let you know if the MAP sensor is defective or not. The entire test is explained in detail so that you can find out if it's defective or not.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (2007-2010 2.2L Chevrolet Cobalt) (at: autotecnico-online.com).
This tutorial applies to the following vehicles since they use the exact same MAP sensor:
- 2007, 2008, 2009, 2010 2.2L Chevrolet Cobalt.
- 2007, 2008, 2009 2.2L Pontiac G5.
Symptoms Of A Bad MAP Sensor
One of the MAP sensor's jobs is to inform the fuel injection computer of the barometric pressure of the surrounding air as you're about to crank and start the engine.
The other one is to inform the computer of engine load as you step on or off the accelerator pedal.
Since this information is critical for optimal engine performance, when the MAP sensor fails the fuel injection computer is going to light up to check engine light with a MAP sensor trouble code. You'll see one of the following trouble codes:
- DTC P0107 MAP Sensor Circuit Low Voltage.
- DTC P0108 MAP Sensor Circuit High Voltage.
Besides a MAP sensor trouble code and the check engine light being on, you'll see one or more of the following symptoms:
- Rough idle.
- 'Rotten egg' smell coming from the exhaust.
- Won't pass the state mandated emissions test.
- Bad gas mileage.
- Lack of power, rough idle, or hesitation.
- Engine cranks a long time before starting.
MAP Sensor Circuit Descriptions
The MAP sensor is a 3-wire type sensor. This means that it has a power wire, a Ground wire and a signal wire. The table below has a brief description of each:
| Terminal | Wire | Description |
|---|---|---|
| 1 | LT GRN | MAP Signal |
| 2 | ORG/BLK | Ground |
| 3 | GRY | 5 Volts |
Where To Buy The MAP Sensor And Save
The MAP sensor isn't an expensive component but it can get pricey depending on where you decide to buy it (the AC Delco MAP sensor runs about $40 at the auto parts store and $12 online).
The following links will help you to comparison shop and hopefully save you a few bucks on its purchase (I've also included the link to the MAP sensor electrical connector):
NOTE: The above manifold absolute pressure (MAP) sensor fits the 2007-2010 2.2L Chevrolet Cobalt and the 2007-2009 2.2L Pontiac G5.
TEST 1: Testing The MAP Sensor Voltage Signal
The most accurate way to test the MAP sensor isn't with a scan tool. It's with a multimeter.
To be a bit more specific, the multimeter is connected to the MAP sensor's signal wire and vacuum is manually applied to it (with a vacuum pump or with the mouth).
As vacuum is being applied to the MAP sensor, the multimeter should show the voltage of the signal decreasing.
As vacuum is released, the voltage signal should go back up to the voltage value you saw at the beginning of the test.
If the MAP sensor is defective, the voltage value of the MAP signal will stay stuck in one number as you apply/release vacuum.
NOTE: If you don't have a vacuum pump you can use your mouth to apply vacuum to the MAP sensor. If you would like to buy a vacuum pump, check out this link: HTOMT 2 In 1 Vacuum Pump Test Set.
IMPORTANT: The manifold absolute pressure (MAP) sensor must remain connected to its electrical connector for this test to function properly. To be able to access the voltage inside the signal wire, you'll need to use either a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.
Let's get started:
- 1
Remove the MAP sensor from the intake manifold.
- 2
Connect your vacuum pump to the MAP sensor's vacuum inlet port. Reconnect the MAP sensor to its connector if you disconnected it.
- 3
Set your multimeter's selector to Volts DC mode and with the red test lead, probe the LT GRN wire of the MAP sensor's connector. This wire is identified by the number 1 in the photo above.
Remember, the MAP sensor must remain connected to its 3-wire connector. - 4
Ground the black multimeter test lead directly on the battery negative (-) terminal.
- 5
Turn the key ON but don't start the engine. This will power up the MAP sensor and you should see a reading of 4.7 Volts DC on your multimeter.
- 6
Now, apply vacuum to the MAP sensor with the vacuum pump (or your mouth). The voltage signal value should decrease.
If you're using a vacuum pump: At 5 in.Hg → 3.9 Volts. At 10 in.Hg → 3 Volts. At 15 in.Hg → 2.1 Volts. At 20 in.Hg → 1.2 Volts. - 7
Release the vacuum. Once released, your multimeter should show the original voltage value.
Repeat this test step several times making sure that each time the voltage decreases/increases as you apply/release vacuum.
Let's take a look at what your test results mean:
CASE 1: The MAP voltage signal decreased and increased as you applied and released vacuum. This is the correct test result and lets you know that the MAP sensor is working correctly (not defective).
This test result also lets you conclude that the MAP sensor is getting both power (5 Volts) and Ground from your 2.2L Chevy Cobalt or Pontiac G5's fuel injection computer.
CASE 2: The MAP voltage signal DID NOT decrease/increase as you applied and released vacuum. This test result usually indicates that the MAP sensor is defective.
To make sure the MAP sensor is truly defective we have to make sure that it's getting both power and Ground. For these tests go to: TEST 2: Verifying MAP Sensor Has 5 Volts And Ground.
CASE 3: The multimeter DID NOT register any voltage. This test result usually indicates that the MAP sensor is defective.
To make sure the MAP sensor is truly defective we have to make sure that it's getting both power and Ground. For these tests go to: TEST 2: Verifying MAP Sensor Has 5 Volts And Ground.
