The manifold absolute pressure (MAP) sensor, on your 1.5L Honda Civic, can easily be tested with just a multimeter. In other words, you don't need a scan tool to find out if it's bad or not.
In this tutorial, I'll show you how to test the MAP sensor in action (but without the engine running), in a step-by-step way, so that you can have the certainty that the money you're gonna' spend on a new part will actually solve the problem.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1.5L Honda Civic) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 1.5L Honda Civic: 1992, 1993, 1994, 1995.
- 1.5L Honda Civic Del Sol: 1993, 1994, 1995.
MAP SENSOR -WHAT DOES IT DO?:
TPS SENSOR DIAGNOSTIC TESTS:
Symptoms Of A Bad MAP Sensor
The fuel system on your 1.5L Honda Civic is a speed-density type. In layman's terms, this means the fuel injection computer needs to know engine speed (RPM), intake manifold pressure, and intake air temperature.
With that info, the computer can calculate the amount of air entering the engine and inject the correct amount of fuel.
It's the MAP sensor's job to report intake manifold pressure (vacuum) to your Civic's fuel injection computer. Because of the critical role the MAP sensor plays in engine management, when it fails, you'll see the following trouble code light up the check engine light on the instrument cluster:
- Code 3: MAP Sensor Circuit.
Besides the check engine light illuminated with a Code 3, you're going to see one or more of the following engine performance issues:
- Rough idle.
- 'Rotten egg' smell coming from the exhaust.
- Bad gas mileage.
- Lack of power, rough idle, or hesitation.
- Engine cranks a long time before starting.
NOTE: You can find out more about the role that the MAP sensor plays in your Civic's engine management system in this guide:
Map Sensor Circuit Descriptions
The MAP sensor's connector has three wires coming out of it. And in the table below, you'll find a brief description of what each circuit does:
| 1992-1995 1.5L Honda Civic DX/LX | ||
|---|---|---|
| Pin | Wire | Description |
| 1 | Yellow with red stripe (YEL/RED) | 5 Volts |
| 2 | Green with white stripe (GRN/WHT) | Ground |
| 3 | White (WHT) | MAP Signal |
| 1992-1995 1.5L Honda Civic CX | ||
|---|---|---|
| Pin | Wire | Description |
| 1 | Yellow with green stripe (YEL/GRN) | 5 Volts |
| 2 | Green with blue stipe (GRN/BLU) | Ground |
| 3 | Pink with white stripe (PNK/WHT) | MAP Signal |
Where To Buy The MAP Sensor And Save
If, after testing your Civic's MAP sensor, you find it's fried, I recommend the following two sensors from trusted automotive brands I've used many times over the years —and that I don't hesitate to recommend:
23%Disclosure: As an Amazon Associate, I earn from qualifying purchases. If my tutorials help you, using these links is an easy way to support the site at no extra cost to you. Thank you!
NOTE: If you're not sure if the above MAP sensor fit your particular 1.5L Civic 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: Testing The MAP Sensor Voltage Signal
As you're probably already aware, when the engine idles and manifold vacuum pressure is low, the MAP sensor produces a high voltage signal.
When manifold vacuum is high, like when you accelerate the engine, the MAP sensor produces a low voltage signal.
When a MAP sensor fails, it'll usually stay stuck at one specific voltage value irrespective of the amount of vacuum applied to it.
To get our MAP sensor diagnostic under way, we're gonna' dive right in and verify that the MAP sensor's voltage signal changes depending on the amount of vacuum we manually apply to the sensor with a vacuum pump.
If you don't have a multimeter and need to buy one, check out my recommendations here: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).
IMPORTANT: The MAP sensor needs to stay connected to its electrical connector for this test to work. You'll need to use a back-probe or a wire-piercing probe to measure the MAP signal voltage. To see what a wire-piercing probe looks like, go here: Goupchn 4mm Banana to Banana Plug Test Leads Kit (Amazon affiliate link).
Here are the 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 WHT or PNK/WHT wire of the MAP sensor's connector.
Remember, the MAP sensor must remain connected to its 3-wire connector. - 5
Connect the black multimeter test lead directly to the battery negative (-) terminal.
- 6
When everything is ready, turn the key to the ON position 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).
- 8
The voltage signal value should decrease as you apply vacuum to the MAP sensor.
- 9
Release the vacuum. Once released, your multimeter should show the original voltage value.
- 10
Apply and release vacuum to the MAP sensor several times to make sure that each time the voltage decreases/increases (as you apply/release vacuum).
Let's take a look at your test results:
CASE 1: The MAP voltage signal decreased and increased as you applied and released vacuum. This test result confirms that the MAP sensor is OK and not defective.
CASE 2: The MAP voltage signal DID NOT increase (and/or decrease) as you applied and released vacuum. This test result confirms the manifold absolute pressure (MAP) trouble code lighting up the check engine light on your 1.5L Honda Civic.
If I where in your shoes and to be sure that the MAP sensor has truly failed, I would still make sure that the MAP sensor is getting both power and Ground. To check for power on the LT GRN wire, go to: TEST 2: Making Sure The MAP Sensor Is Getting Power.
CASE 3: The multimeter DID NOT register any voltage. This test result doesn't condemn the MAP sensor as bad just yet. Why?
Because the MAP sensor may be missing either power or Ground. So the next step is to check that the MAP sensor is getting power, go to: TEST 2: Making Sure The MAP Sensor Is Getting Power.
TEST 2: Making Sure The MAP Sensor Is Getting Power
If in TEST 1 the MAP sensor's voltage signal value does not move down or up, then the next step is to make sure it gets power (5 Volts DC). Why?
Because if it's missing power, it won't produce the decrease/increase in voltage signal you were looking for (and you might end up replacing the TPS when your Civic doesn't need it).
Depending on the specific trim level of your Honda Civic, this 5 Volt supply wire will be:
- On 1.5L Civic DX and LX models:
- The yellow with red stripe (YEL/RED) wire.
- On 1.5L Civic CX models:
- The yellow with green stipe (YEL/GRN) wire.
OK, this is what you need to do:
- 1
Disconnect the MAP sensor from its 3-wire connector.
- 2
Connect the black multimeter test lead to the battery negative (-) post.
- 3
Set the multimeter to Volts DC mode.
- 4
Turn the key to the ON position but don't crank or start the engine.
- 5
Gently probe the female terminal 1 of the connector with the red multimeter test lead.
Check that terminal 1 corresponds to the YEL/RED (or YEL/GRN) wire of the connector. - 6
The multimeter should register 4.5 to 5 Volts DC.
Let's take a look at what your test results mean:
CASE 1: The multimeter confirms that the MAP sensor is fed 4.5 to 5 Volts. Great, this test result tells us that the MAP sensor gets power.
Your next step is to make sure the MAP sensor gets Ground from your Civic's fuel injection computer. For this test, head over to: TEST 3: Making Sure The MAP Sensor Is Getting Ground.
CASE 2: The multimeter confirms that the MAP sensor IS NOT fed 4.5 to 5 Volts. Double-check that you're testing the correct MAP sensor connector terminal wire and repeat the test.
If your multimeter still doesn't show the indicated voltage, then we can conclude:
- There's an open-circuit issue in the power supply wire between the MAP sensor connector and the FI computer connector.
- Your Civic's fuel injection computer has an internal problem (although this is very rare).
Although testing these two conditions is beyond the scope of this tutorial, you've now eliminated the MAP sensor as the cause of the problem and/or the MAP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL) on your 1.5L Honda Civic.
TEST 3: Making Sure The MAP Sensor Is Getting Ground
Up to this point, your Civic's TPS diagnostic tests confirmed the following:
- The MAP sensor voltage signal is stuck at one value (TEST 1).
- The sensor is getting 5 Volts (TEST 2).
For our final test, we'll make sure your Civic's fuel injection computer is supplying Ground to the MAP sensor.
Depending on the specific trim level of your Honda Civic, this Ground is delivered by one of the following wires:
- On 1.5L Civic DX and LX models:
- The green with white stripe (GRN/WHT) wire.
- On 1.5L Civic CX models:
- The green with blue stripe (GRN/BLU) wire.
To check for the presence of this computer-supplied Ground, we'll do a multimeter voltage test.
IMPORTANT: Your Honda Civic's fuel injection computer feeds Ground to the MAP sensor internally. Be careful not to short the Ground wire (circuit) to battery voltage or you'll fry the computer. The multimeter voltage test I'm suggesting in the test instructions is a safe way to confirm the presence of Ground in this circuit.
OK, this is what you need to do:
- 1
Disconnect the MAP sensor from its 3-wire connector.
- 2
Connect the red multimeter test lead to the battery positive (+) post.
- 3
Set the multimeter to Volts DC mode.
- 4
Turn the key to the ON position but don't crank or start the engine.
- 5
Gently probe the female terminal 2 of the connector with the black multimeter test lead.
Check that terminal 2 corresponds to the GRN/WHT (or GRN/BLU) wire of the connector. - 6
The multimeter should register 10 to 12 Volts DC.
Let's take a look at what your test results mean:
CASE 1: The MAP sensor is getting Ground. This is the expected and correct test result.
Now, you can confidently conclude that the MAP sensor is bad only if:
- You confirmed that the MAP sensor voltage signal did not increase/decrease while you applied/released vacuum in TEST 1.
- You confirmed that the MAP sensor got power (5 Volts) in TEST 2.
- You confirmed that the MAP sensor got Ground in this test.
If you're ready to replace the MAP sensor on your 1.5L Honda Civic, these are the two sensors I recommend from known automotive brands I don't hesitate to recommend:
- Standard Motor Products AS64T MAP Sensor (Amazon affiliate link).
- Beck/Arnley 158-0880 MAP Sensor (Amazon affiliate link).
CASE 2: The MAP sensor IS NOT fed Ground. Double-check that you're testing the correct connector terminal and repeat the test.
If your multimeter still doesn't show the sensor gets Ground, the sensor itself is not the cause of the engine performance issue or the MAP trouble code.
The most likely cause of this missing Ground is:
- An open-circuit issue in the wire between the MAP sensor connector and the FI computer connector.
- The fuel injection computer has an internal problem (although this is very rare).
Although testing these two conditions is beyond the scope of this tutorial, your next step is to find out why this Ground is missing and restore it to the circuit to get the MAP sensor working again.
More 1.5L Honda Civic Tutorials
You can find a complete list of 1.5L Honda Civic tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test The PGM-FI Main Relay (1992-1995 1.5L Honda Civic).
- How To Test The Throttle Position Sensor (1992-1995 1.5L Honda Civic).
- How To Test Engine Compression (1992-1995 1.5L Honda Civic).
- How To Test The Fuel Pump In 2 Tests (1992-1995 1.5L Honda Civic).
- How To Test The Igniter, Ignition Coil Accord, Civic, CRV, And Odyssey (at easyautodiagnostics.com).
If this info saved the day, buy me a beer!
