This article will show you a very accurate way to diagnose a Manifold Absolute Pressure (MAP) Sensor Diagnostic Trouble Code P0108, P0109 or a BAD MAP sensor with a multimeter and a vacuum pump.
The MAP Position Test is divided into three parts, and so... to help you navigate this article, here are the contents of this article at a quick glance:
- Symptoms of a BAD MAP.
- MAP SENSOR TEST 1: Checking the MAP Signal With a Multimeter.
- MAP SENSOR TEST 2: Making Sure the MAP Sensor is Getting 5 Volts.
- MAP SENSOR TEST 3: Making Sure the MAP Sensor is Getting Ground.
- MAP Code Will Not Go Away.
- How the MAP Sensor Works.
- Where to Buy the MAP Sensor and Save.
Also, this articles covers vehicle from Chrysler, Dodge, Plymouth, Eagle and Mitsubishi (2.0L, 2.4L, 2.5L, 3.3L, 3.8L) and to see if this article applies to your specific vehicle take a look at the Applies To container on the column on the left.
If you need the Chrysler 4 wire MAP sensor test, go here:
The following OBD II code tutorials will also help you diagnose your MAP sensor:
- P0107 MAP Sensor OBD II Trouble Code (at: troubleshootmyvehicle.com).
- P0108 MAP Sensor OBD II Trouble Code (at: troubleshootmyvehicle.com).
You'll find several Chrysler ‘How to Test’ articles by checking out the: Chrysler Index of Articles.
You can find this tutorial in Spanish here: Cómo Probar el Sensor MAP de Chrysler (de 3 Cables) (at: autotecnico-online.com).
Your Chrysler's fuel system (and by extension, the ignition system), depend on the info that the MAP sensor feeds the fuel injection computer.
So, when the MAP sensor fails, you'll have the check engine light (CEL) shining nice and bright on your instrument cluster and sever engine performance problems. You'll see one (or more) of the following symptoms:
- MAP Sensor Diagnostic Trouble Code (DTC) P0107, P0108 stored in the vehicle's computer's memory.
- P0107: MAP Sensor Voltage Too Low. To learn more about DTC P0107, check out the following tutorial: P0107 MAP Sensor OBD II Trouble Code (at: troubleshootmyvehicle.com).
- P0108: MAP Sensor Voltage Too High. To learn more about DTC P0108, check out the following tutorial: P0108 MAP Sensor OBD II Trouble Code (at: troubleshootmyvehicle.com).
- 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 out momentarily as you step on the gas to get the vehicle moving.
The Manifold Absolute Pressure (MAP) sensor produces a DC Voltage Signal that varies according to the amount of engine vacuum present in the intake manifold. So the very first thing you'll do, is to verify that the MAP sensor is producing a healthy MAP Signal that the PCM (Powertrain Control Module= Fuel Injection Computer) can use.
This is a pretty easy test and on which should take you about 15 minutes or less to do. If you don't own a vacuum pump, you can rent one from your local AutoZone (or O'Reilly Auto Parts). OK, let's start:
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: Abe's Digital Multimeter Recommendation.
With the engine off, remove the MAP sensor from the intake manifold. If you needed 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).
Select Volts DC Mode on your multimeter and with the RED multimeter lead probe the wire identified by the number 3 in the image viewer.
The color of the wire may not be the same one as the one in the image viewer on your specific Chrysler (Dodge, Eagle, Plymouth, Mitsubishi) car or mini-van. This is nothing to worry about since you'll be able to test the correct circuit using the image as a guide.
Ground the BLACK multimeter Test Lead on the Battery Negative Terminal and then have your helper turn the Key On but don't start the engine.
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.
Now, connect your vacuum pump to the MAP sensor using a large diameter hose (I use a 3/8 fuel hose).
Whatever hose you use, it's important that it makes a tight seal on both the MAP sensor's vacuum inlet nipple and the vacuum hose.
OK, now actuate the vacuum pump till the gauge's needle reaches 5 in. Hg of vacuum. These are the readings you should have as you pump the vacuum pump to different vacuum levels:
- 1.) 0 in. Hg ...... 4.7 Volts.
- 2.) 5 in. Hg ...... 3.9 Volts.
- 3.) 10 in. Hg .... 3.0 Volts.
- 4.) 15 in. Hg .... 1.1 Volts.
The readings on your vacuum pump's Gauge may be a little different, but the idea is that as you increase vacuum, the voltage reading will decrease in a smooth and linear fashion (without any gaps or crazy readings). Once you release the vacuum you've applied, the voltage reading should go back down to the value you registered in step 4.
Let's take a look at what your test results mean:
CASE 1: As you applied vacuum, the Voltage decreased in a smooth linear way with no gaps, then the Manifold Absolute Pressure (MAP) sensor is working like it should and is not the cause of the issue. No further MAP sensor tests are needed.
Now, if the MAP sensor 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 vacuum, the Voltage DID NOT decrease in a smooth linear way and/or there were gaps, this results confirms that the MAP sensor is fried and that it needs to be replaced. Replacing the MAP sensor will solve the issue.
CASE 3: If 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 MAP sensor may not be getting a supply of either Power or Ground. To test this go to MAP SENSOR TEST 2.