How To Test The MAP Sensor (1994-1997 2.2L Accord, Odyssey, Prelude)

Testing the MAP sensor is not hard.

This tutorial will help you to test the manifold absolute pressure (MAP) sensor with a multimeter. Although a scan tool is a handy tool to have, you don't need one to test the MAP sensor.

With your test results you'll be able to easily find out if the MAP sensor is bad or not.

And I'm also going to show you where you can buy the MAP sensor in case it's bad.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1994-1997 2.2L Accord, Odyssey, Prelude) (at: autotecnico-online.com).

APPLIES TO: This tutorial, on how to test the MAP sensor, applies to the following vehicles:

• 2.2L Honda Accord: 1994, 1995, 1996, 1997.
• 2.2L Honda Odyssey: 1995, 1996, 1997.
• 2.2L Honda Prelude: 1994, 1995, 1996, 1997.

Symptoms Of A Bad MAP Sensor

The fuel injection computer in your Honda Accord (Odyssey or Prelude) needs to know three things to be able to calculate the correct amount of air entering the engine.

These three things are intake air temperature, engine RPM, and engine load.

Once the computer has figured out how much air is entering the engine, it can now calculate the correct amount of fuel to inject into the engine.

The sensor that informs the computer of engine load is the manifold absolute pressure (MAP) sensor.

Since the MAP sensor is such a critical component of the engine management system, when it fails you're going to see the check engine light illuminated by one of the following trouble codes:

• P0107: MAP Sensor Voltage Too Low.
• P0108: MAP Sensor Voltage Too High.

You're also gonna' see one or more of the following symptoms:

• Bad gas mileage.
• Black smoke coming out of the tail pipe, especially when you accelerate the vehicle.
• No power and/or hesitation as you accelerate the vehicle. It feels like all of a sudden someone cut the power momentarily as you step on the accelerator pedal.

How The MAP Sensor Works

The MAP sensor is able to inform the fuel injection computer of the engine's load by measuring the vacuum inside the intake manifold.

So here, in a nutshell, is how the MAP sensor works when you crank and start your 2.2L Honda Accord (Odyssey or Prelude):

1. The fuel injection computer supplies 5 Volts and Ground to the MAP sensor.
2. At idle the MAP sends the PCM computer a DC voltage signal of about 1.1 to 1.8 Volts.
3. When you step on the accelerator pedal to accelerate the engine, vacuum immediately increases which causes the MAP signal voltage to the computer to decrease.
4. With this decreasing voltage signal, the computer knows it's time to inject more fuel, advance ignition timing, and a host of other things it has to do to keep your Honda running optimally.
5. As you let go off the accelerator pedal to slow down, the throttle plate closes and of course the MAP sensor sends the info to the computer as it returns to its idle voltage signal, till the whole cycle begins again.

Pretty easy stuff? The cool thing is that testing the MAP sensor's performance is easy too.

Where To Buy The MAP Sensor And Save

The following links will help you to comparison shop for the MAP sensor and save a few bucks!:

If you're not sure if the above MAP sensor fits your particular 2.2L Honda Accord (Odyssey or Prelude) don't worry, once you get to the site, they'll make sure the sensor is the right one, if not, they'll find you the right one.

TEST 1: Checking The MAP Signal With A Multimeter

For our very first test, we're going to remove the MAP sensor and manually apply vacuum to it with a vacuum pump while we check its signal voltage with a multimeter.

The purpose of this test is to see if the MAP sensor's voltage signal decreases when we apply vacuum and increases when we release vacuum.

If the MAP sensor is bad, you'll notice that the MAP voltage signal will stay stuck at one value as you apply/release vacuum to it.

If you don't have a vacuum pump, no worries. You can run down to your local auto parts store and borrow one from them or you can use your mouth to apply vacuum to the sensor.

NOTE: You'll need a multimeter to test your vehicle's MAP sensor. If you don't have one and need to buy one or upgrade yours, the following recommendation will help: Buying A Digital Multimeter For Automotive Diagnostic Testing.

IMPORTANT: The MAP sensor must remain connected to its electrical connector to read its voltage signal. You'll need to use a back-probe on the connector or a wire-piercing probe on the wire to access the MAP signal. You can see an example of this tool here: Wire Piercing Probe Review.

OK, let's start:

1. 1

   Remove the MAP sensor from the intake manifold. If you had to disconnect the MAP sensor from it's electrical connector to remove it, reconnect it now (the MAP sensor must remain connected to its connector for this test).

2. 2

   Connect the vacuum pump to the MAP sensor's vacuum inlet port.

3. 3

   Select Volts DC Mode on your multimeter.

4. 4

   Connect the red multimeter test lead to the white with yellow stripe (WHT/YEL) wire of the MAP sensor's connector.
   
   In the photo above I've identified the WHT/YEL wire with the number 3.
   
   NOTE: The MAP sensor must remain connected to its electrical connector to test the MAP signal voltage.

5. 5

   Ground the black multimeter test lead on the battery negative (-) terminal.

6. 6

   Have your helper turn the key On but don't start the engine.

7. 7

   You should see a voltage around 4.5 Volts DC registering on your multimeter. If it doesn't, don't worry about it just yet, continue with the other steps.

8. 8

   Apply vacuum to the MAP sensor till the gauge's needle reaches 5 in. Hg of vacuum. These are the approximate readings you should see as you apply vacuum to the sensor:
   
   1.) 0 in. Hg ...... 3-4 Volts.
   
   2.) 5 in. Hg ...... 2.4 Volts.
   
   3.) 10 in. Hg .... 1.9 Volts.
   
   4.) 15 in. Hg .... 1.4 Volts.

9. 9

   Release the vacuum you've applied. The voltage reading should go back up to the value you registered in step 7.

Let's take a look at what your test results mean:

CASE 1: As you applied/released vacuum, the voltage decreased/increased. This is the correct test result.

You can conclude that the manifold absolute pressure (MAP) sensor is working fine and is not defective. No further MAP sensor tests are needed.

Now, if the MAP sensor trouble code won't go away, take a look at the info found at: MAP Code Will Not Go Away for a few more suggestions as to what could be causing the MAP sensor diagnostic trouble code (DTC).

CASE 2: As you applied/released vacuum, the voltage DID NOT decrease/increase. This test result usually confirms that the MAP sensor is fried and that it needs to be replaced. But before you replace it, make sure it's getting 5 Volts and Ground.

The next test is to make sure that the MAP sensor is getting 5 Volts. Go to: TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.

CASE 3: The multimeter DID NOT register any voltage. This isn't good, but doesn't condemn the manifold absolute pressure (MAP) sensor as bad yet.

The next test is to make sure that the MAP sensor is getting 5 Volts. Go to: TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.