You can test the manifold absolute pressure (MAP) sensor easily and accurately with a multimeter; no scan tool is required. In this tutorial, I'll explain the testing process step by step.
Your test results will quickly determine if the MAP sensor is good or bad.
Contents of this tutorial:
- Symptoms Of A Bad MAP Sensor.
- Where To Buy The MAP Sensor And Save.
- MAP Sensor Circuit Descriptions.
- TEST 1: Testing The MAP Sensor Signal.
- TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
- TEST 3: Making Sure The MAP Sensor Is Getting Ground.
- MAP Sensor Code Won't Go Away.
- More 2.2L Buick Century And Oldsmobile Cutlass Ciera Test Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.2L Buick Century: 1993, 1994, 1995, 1996.
- 2.2L Oldsmobile Cutlass Ciera: 1993, 1994, 1995.
- 2.2L Oldsmobile Ciera: 1996.
Symptoms Of A Bad MAP Sensor
The MAP sensor provides critical engine load information to the engine management system (the fuel injection computer).
When the MAP sensor fails, the fuel injection computer will illuminate the check engine light and set one of the following diagnostic trouble codes:
OBD I:
- 33: MAP Sensor Signal Voltage High.
- 34: MAP Sensor Signal Voltage Low.
OBD II:
- P0106: MAP Sensor System Performance.
- P0107: MAP Sensor Circuit Low Voltage.
- P0108: MAP Sensor Circuit High Voltage.
You'll also see one or more of the following symptoms:
- The engine won't start.
- The engine takes a long time to start (extended cranking time).
- Black smoke coming out of the tailpipe.
- Bad gas mileage.
- The engine idles rough when running.
- A lack of power when under load.
Where To Buy The MAP Sensor And Save
The following links will help you comparison shop for the manifold absolute pressure (MAP) sensor. The recommended MAP sensors are of known automotive brands -no knockoff MAP sensors!
Not sure if the MAP sensor fits your vehicle? Don't worry. Once you get to the site, they'll make sure it fits by asking you the specifics of your vehicle. If it doesn't fit, they'll find you the right MAP sensor.
MAP Sensor Circuit Descriptions
| Wire | Color | Description |
|---|---|---|
| A | Black (BLK) | Ground |
| B | Light green (LT GRN) | MAP signal |
| C | Grey (GRY) | 5 Volts |
TEST 1: Testing The MAP Sensor Signal
Generally, when the MAP sensor fails, its voltage signal stays stuck in one value regardless of the amount of vacuum pressure it receives.
To find out if the MAP sensor is bad, you'll apply/release vacuum to it as you check its voltage output signal.
If the MAP sensor is OK, its voltage output signal will decrease/increase as you manually apply/release vacuum to it (with a vacuum pump).
NOTE: If you don't have a vacuum pump, don't worry. You can use your mouth to apply vacuum to the MAP sensor.
IMPORTANT: The MAP sensor must remain connected to its electrical connector to read the voltage within its signal wire. You'll need to use a back probe on the connector or a wire piercing probe on wire. You can see an example of this tool here: Wire Piercing Probe.
OK, these are the test steps:
- 1
Remove the MAP sensor from its place on the intake manifold.
- 2
If you had to disconnect the MAP sensor from its electrical connector to remove it, reconnect it to the connector now.
- 3
Connect your vacuum pump to the MAP sensor's vacuum inlet.
You'll need to use a piece of vacuum hose to connect the vacuum pump to the MAP sensor. - 4
Place your multimeter in Volts DC mode.
- 5
Connect the red multimeter probe to the wire labeled with the letter B (in the image above).
The wire labeled with the letter B is the light green (LT GRN) wire of the connector.
IMPORTANT: The MAP sensor must remain connected to its 3 wire connector. - 6
Connect the black multimeter test lead directly to the battery negative (-) terminal.
- 7
Turn the key ON but don't start the engine.
- 8
At this point your multimeter should register a value around 4.5 Volts DC.
- 9
Now, pump the vacuum pump to apply vacuum to the MAP sensor. The voltage should decrease.
- 10
Release the vacuum you applied to the MAP sensor. The voltage should increase.
OK, let's examine your test results:
CASE 1: The MAP voltage signal decreased/increased as you applied/released vacuum to the sensor. This is the correct result and confirms that the MAP sensor is functioning correctly.
If a MAP sensor diagnostic trouble code still illuminates the check engine light, you can conclude the MAP sensor itself is not the cause. For more info, take a look at the section: MAP Sensor Code Won't Go Away.
CASE 2: The MAP voltage signal DID NOT increase/decrease as you applied/released vacuum. This test result usually indicates that the MAP sensor is bad.
Before replacing the MAP sensor, you need to make sure that it's getting power and Ground. Go to the next test: MAP TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
CASE 3: Your multimeter registered 0 Volts. This test result generally tells you that the MAP sensor is bad.
Before replacing the MAP sensor, you need to make sure that it's getting power and Ground. Go to the next test: MAP TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
