In this tutorial, I'm going to show you a very accurate way to test the MAP sensor ,on the 2008-2012 2.4L Chevrolet Malibu (Pontiac G6), and find out if it's defective or not.
Since the manifold absolute pressure (MAP) sensor is a simple 3 wire component, it can be easily tested with a multimeter.
This tutorial applies to the following vehicles since they use the exact same MAP sensor:
- 2008, 2009 2.4L Chevrolet Malibu.
- 2010, 2011, 2012 2.4L Chevrolet Malibu LS, LT, and LTZ.
- 2008, 2009, 2010 2.4L Pontiac G6.
Contents of this tutorial at a glance:
Symptoms Of A Bad MAP Sensor
The MAP sensor is a key component of your 2.4L Chevrolet Malibu or Pontiac G6's engine management system.
One of its functions is to let the fuel injection computer know what load the engine is under by measuring the amount of vacuum inside the intake manifold.
In a nutshell, the more the engine is under load, the more intense the vacuum pressure is that's supplied to the MAP sensor.
This causes the MAP sensor to create a voltage signal that corresponds to the amount of vacuum it's receiving.
So when the MAP sensor fails, you're going to see one of the following trouble codes lighting up the check engine light:
- DTC P0107 MAP sensor Circuit Low Voltage.
- DTC P0108 MAP sensor Circuit High Voltage.
You're also going to 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.
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 can cost an arm and a leg at your local auto parts store (my local auto parts store sells the AC-Delco MAP sensor for $113!! You can buy it online for around $35! -see link below). Take a look at the following links and comparison shop because I think you'll save a few bucks by buying it online.
NOTE: The above MAP sensors fit the 2008-2009 2.4L Chevrolet Malibu, 2010-2012 2.4L Chevrolet Malibu LS (and LT, LTZ), 2008-2010 2.4L Pontiac G6.
TEST 1: Testing The MAP Sensor Voltage Signal
To find out if the MAP sensor is defective (or not), on your 2.4L Chevy Malibu or 2.4L Pontiac G6, we're going to connect a multimeter to its MAP signal wire and then we're going to manually applying vacuum to it.
If the MAP sensor is working correctly, as we apply vacuum to it its voltage signal should decrease.
And as we release the vacuum that we're applying to it, it's voltage signal should increase.
If the MAP sensor is defective you'll see that it's voltage signal stays stuck in one value as you apply/release vacuum to it.
IMPORTANT: The MAP sensor must remain connected to its electrical connector to be able to read its voltage signal. To access the voltage signal inside the wire you'll need to use a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.
These are the test steps:
- 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.
- 4
Connect the red test lead to 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. - 5
Ground the black multimeter test lead directly on the battery negative (-) terminal.
- 6
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.
- 7
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 → 2.2 Volts. At 10 in.Hg → 3 Volts. At 15 in.Hg → 2.1 Volts. At 20 in.Hg → 1.2 Volts. - 8
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/increased as you applied/released vacuum. This is the correct test results and it confirms that the manifold absolute pressure (MAP) sensor is working correctly on your 2.4L Chevrolet Malibu (Pontiac G6).
With this test result you can also conclude that the MAP sensor is getting 5 Volts and Ground from your 2.4L Chevy Malibu's fuel injection computer. No further testing of the MAP sensor is required.
This test result also tells you that the MAP sensor is getting 5 Volts and Ground and no further testing is required.
CASE 2: The MAP voltage signal DID NOT decrease/increase as you applied/released vacuum. This test result usually indicates that the MAP sensor is defective but not always.
In some cases the MAP sensor does not create a decreasing/increasing voltage signal because it's missing 5 Volts or Ground. The good thing is that testing for the presence of these 5 Volts and Ground is not hard. 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 but not always.
In some cases the MAP sensor does not create a decreasing/increasing voltage signal because it's missing 5 Volts or Ground. The good thing is that testing for the presence of these 5 Volts and Ground is not hard. For these tests go to: TEST 2: Verifying MAP Sensor Has 5 Volts And Ground.
