The MAP sensor, on the 2006-2007 3.9L Chevrolet Malibu and Impala can be tested very easily with just a simple multimeter.
This test is so accurate that with its results you'll be able to find out if it's defective or not.
In this tutorial, I'll show you how to do it in a step-by-step manner.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (2006-2007 3.9L Chevrolet Malibu) (at: autotecnico-online.com).
Symptoms Of A Bad MAP Sensor
Even though your 3.9L V6 Chevrolet Malibu or Chevrolet Impala comes equipped with a mass air flow (MAF) sensor, it still uses a manifold absolute pressure (MAP) sensor.
The MAP sensor is tasked with giving the fuel injection computer barometric pressure information and engine load information (once the engine is up and running).
Needless to say the manifold absolute pressure (MAP) sensor is a crucial component of the engine management system.
So when it fails you're definitely going to see engine performance problems and the check engine light will be lit up by one of the following map sensor trouble codes:
- 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 |
|---|---|---|
| A | ORG/BLK | Ground |
| B | LT GRN | MAP Signal |
| C | 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 2006-2007 3.9L V6 Chevrolet Malibu and Impala.
TEST 1: Testing The MAP Sensor Voltage Signal
Testing the MAP sensor consists of connecting a multimeter to the MAP signal wire and then applying vacuum to the MAP sensor to see if the signal voltage decreases as vacuum is applied to it.
The MAP signal wire is the middle one of the connector and is labeled with the letter B in the photo above.
The most common test result of a defective MAP sensor is a voltage signal that stays stuck in one value as you apply and release vacuum to it.
You'll notice that in the test instructions below I'm recommending that you use a vacuum pump. If you don't have one, no worries. You can use your mouth to apply a vacuum to the MAP sensor.
IMPORTANT: To be able to read the MAP sensor voltage signal the MAP sensor must remain connected to its electrical connector. 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.
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.
- 4
Connect the red test lead to the LT GRN wire of the MAP sensor's connector. This wire is identified by the letter B 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 → 3.9 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 test result confirms that the MAP sensor is functioning correctly and is not defective.
This rest result also confirms that the MAP sensor is getting 5 Volts and Ground from your Malibu or Impala's fuel injection computer.
CASE 2: The MAP voltage signal DID NOT decrease/increase as you applied/released vacuum. Generally this test result indicates the MAP sensor is defective or that it's not getting 5 Volts or Ground.
So the next step is to make sure that your Malibu or Impala's fuel injection computer is providing 5 Volts and Ground to the MAP sensor. If both of these are present, then you can conclude that the MAP sensor is bad and needs to be replaced. For this test go to: TEST 2: Verifying MAP Sensor Has 5 Volts And Ground.
CASE 3: The multimeter DID NOT register any voltage. Generally this test result indicates the MAP sensor is defective or that it's not getting 5 Volts or Ground.
So the next step is to make sure that your Malibu or Impala's fuel injection computer is providing 5 Volts and Ground to the MAP sensor. If both of these are present, then you can conclude that the MAP sensor is bad and needs to be replaced. For this test go to: TEST 2: Verifying MAP Sensor Has 5 Volts And Ground.
