How To Test The MAP Sensor (2001-2005 1.7L Honda Civic)

TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts

If you've reached this point, there's a good chance that the MAP sensor isn't getting power (5 Volts DC).

The yellow with red stripe (YEL/RED) wire delivers these 5 Volts to the MAP sensor, and in the photo above, I've labeled it with the number 1.

In this test section, you'll confirm that the YEL/RED wire delivers 5 Volts DC to the MAP sensor.

CAUTION: If you probe the front of the connector, be careful not to damage the metal female terminal. If the terminal gets damaged, you'll need to replace the connector.

Let's get started:

1. 1

   Place your multimeter still in Volts DC mode.

2. 2

   Disconnect the MAP sensor from its electrical connector.

3. 3

   Probe the wire labeled with the number 1, in the photo above, with the red multimeter test lead.
   
   The wire labeled with the number 1, in the photo above, is the YEL/RED of the connector.

4. 4

   Now Ground the black multimeter test lead on the battery's negative (-) post.

5. 5

   Turn the key ON but don't start the engine.

6. 6

   Your multimeter should show you a voltage value around 4.5 to 5 Volts DC.

OK, let's take a look at what your results mean:

CASE 1: The multimeter registered 5 Volts. This is the correct and expected test result.

Now that you've confirmed the MAP sensor is getting power, your next test is to make sure that it's getting Ground. Go to: TEST 3: Making Sure The MAP Sensor Is Getting Ground.

CASE 2: The multimeter DID NOT register 5 Volts. Without 5 Volts, the MAP sensor will not function.

Although it's beyond the scope of this tutorial to troubleshoot the cause of these missing 5 Volts, you have now eliminated the MAP sensor itself as bad.

The most likely cause of these missing 5 Volts is an open-circuit problem in the wire between the MAP sensor and the fuel injection connector.

TEST 3: Making Sure The MAP Sensor Is Getting Ground

So far, you have confirmed the following:

• The MAP sensor's voltage signal does not decrease/increase as you apply/release vacuum (TEST 1).
• The MAP sensor is receiving 5 Volts DC (TEST 2).

Your last test is to see if the MAP sensor is receiving Ground.

The wire that delivers Ground to the MAP sensor is the green with white stripe (GRN/WHT) wire of the connector.

In the photo above, I've labeled the GRN/WHT wire with the number 3.

CAUTION: If you probe the front of the connector, be careful not to damage the metal female terminal. If the terminal gets damaged, you'll need to replace the connector.

IMPORTANT: The fuel injection computer supplies Ground to the MAP sensor. Be careful and do not apply battery 12 Volts to this wire, or you'll fry the computer. The multimeter voltage test indicated in the test instructions is a safe way to test for the presence of Ground in the wire.

These are the test steps:

1. 1

   Place your multimeter still in Volts DC mode.

2. 2

   Disconnect the MAP sensor from its electrical connector.

3. 3

   Probe the wire labeled with the number 3 in the image above, with the black multimeter test lead.
   
   The wire labeled with the number 3 is the GRN/WHT wire of the connector.

4. 4

   Connect the red multimeter test lead on the battery's positive (+) post.

5. 5

   Turn the key ON but don't start the engine.

6. 6

   Your multimeter register 10 to 12 Volts DC.

OK, let's interpret your test result:

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct and expected test result. This test result confirms that the MAP sensor is getting Ground.

You can conclude the MAP sensor is bad and needs replacement if you have:

• Confirmed that the MAP sensor's voltage signal does not decrease/increase as you apply/release vacuum to the sensor (TEST 1).
• Confirmed that the MAP sensor is receiving 5 Volts DC (TEST 2).
• Confirmed in this test section that it's receiving Ground.

CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result tells you that the MAP sensor is not receiving Ground. Without Ground the MAP sensor will not function.

With this test result you can eliminate the MAP sensor itself as bad. Your next step is to find out why this Ground is missing and resolve the problem.

The most likely cause of this missing Ground is an open-circuit problem in the wire between the MAP sensor connector and the fuel injection connector.

MAP Sensor Code Won't Go Away

In some cases, a MAP sensor trouble code keeps returning and illuminating the check engine light after replacing the MAP sensor with a new one or after testing it (and confirming the sensor is functioning correctly).

If this is happening in your case, then one or more of the following problems could be behind the issue:

1. The o-ring on the vacuum inlet of the MAP sensor is missing or cracked.
2. The engine has several cylinders with very low engine compression causing it to idle rough and thus producing low or erratic vacuum. For this I suggest an engine compression test.
   • How To Test The Engine Compression (1.7L Honda Civic).
3. The MAP sensor is failing intermittently. Which means that it works fine most of the time, but every now and then it doesn't:
   • I have found that the best way to test these intermittent problems is to slightly tap the MAP sensor with the handle of a screw-driver and see if this tapping screws up the voltage readings as I apply vacuum.
4. The MAP sensor's connector is bad, usually the locking tab is broken and the connector has worked itself loose, causing an intermittent false connection.
5. Your fuel pump is starting to go bad and is not sending enough fuel and/or fuel pressure up to the fuel injectors. I suggest a fuel pump test.

More 1.7L Honda Civic Tutorials

You can find a complete list of 1.7L Honda Civic tutorials in this index:

• Honda 1.7L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test The Crank Sensor (2001-2005 1.7L Honda Civic).
• Maintenance Required Light Reset (2001-05 1.7L Honda Civic).
• How To Do A Cylinder Balance Test (2001-2005 1.7L Honda).
• How To Test The TP Sensor (2001-2005 Honda 1.7L).