Symptoms of a Bad MAP Sensor, and How to Test One

Updated on January 17, 2019
Dan Ferrell profile image

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

MAP sensor on footwell inside engine compartment.
MAP sensor on footwell inside engine compartment. | Source

Bad MAP Sensor Symptoms

A bad manifold absolute pressure (MAP) sensor can upset fuel delivery and ignition timing. Depending on your vehicle model, your engine might experience one or more of these performance problems:

  • Rich air-fuel ratio
  • Lean air-fuel ratio
  • Surging
  • Poor fuel economy
  • It won't start
  • Lack of engine power
  • Stalling
  • Detonation and misfire

However, these symptoms are not exclusively symptoms of a failed MAP sensor. Sometimes, a bad sensor may trigger the check engine light (CEL). If a trouble code has been stored on the computer memory indicating a problem with the MAP sensor, it's a good idea to actually test the sensorm to confirm that the problem lies with the sensor and not some other related component.

What You'll Need to Troubleshoot a MAP Sensor

Troubleshooting a MAP sensor is a straightforward procedure using a digital multimeter (DMM) and a hand-held vacuum pump. If you don't have the pump, your local auto parts store may lend you one.

In the following sections, you'll find some important information about the sensor, what to pay attention to during your inspection, and a simple MAP-sensor test procedure. Keep in mind that these tests apply to gasoline, four-cycle internal combustion engines without a turbo or supercharger. If necessary, consult the vehicle repair manual for your specific model.

Answers You'll Find In This Article

  1. What Does a Map Sensor Do?
  2. Does My Car Have a MAP Sensor?
  3. P0105 and Other MAP Trouble Codes
  4. MAP Sensor Location
  5. How to Test a MAP Sensor
  6. Checking the MAP Sensor Reference Signal
  7. Sensor Voltage Drop Reference Table
  8. Testing a Digital MAP Sensor
  9. MAP Sensor Replacement
  10. Should I Replace the MAP Sensor?

Inspect the map sensor wires for damage during your diagnostic.
Inspect the map sensor wires for damage during your diagnostic. | Source

I. What Does a Map Sensor Do?

Basically, a MAP sensor reads the amount of air pressure in relation to vacuum inside the intake manifold, either directly or using a vacuum hose. Then, it translates this pressure into a voltage signal that the sensor feeds to the power control module (PCM), your car's computer.

The sensor uses a 5 volt reference signal that comes from the computer to return the signal.

Changes in vacuum or air pressure in the intake manifold varies the electrical resistance in the sensor, increasing or reducing the signal’s voltage to the computer.

The PCM uses the MAP sensor’s information along with input from other sensors to adjust fuel delivery to the cylinders and ignition timing according to current engine load and speed.

Some vehicles use a mass air flow sensor (MAF) instead of a MAP sensor. Some use both.
Some vehicles use a mass air flow sensor (MAF) instead of a MAP sensor. Some use both. | Source

2. Does My Car Have a MAP Sensor?

Instead of a MAP sensor, most modern vehicles use a mass air flow (MAF) sensor that the computer uses to calculate air flow along with engine rpm.

Some vehicles come equipped with both a MAP and MAF sensor, usually forced induction systems like turbocharged and supercharged models.

Sometimes, the MAP sensor is used to monitor EGR operation, and doubles as a back up to the MAF sensor.

If you need information regarding your vehicle, consult the repair manual for your particular make and model. You can buy an inexpensive Haynes manual from Amazon. These manuals come with procedures for many maintenance, troubleshooting and replacement component projects. So the manual practically pays for itself after the first maintenance or repair project.

Caution: When Checking Voltages

Use the repair manual for your particular vehicle make and model for diagnostic value specifications.

Use a scanner to download diagnostic trouble codes from your car computer.
Use a scanner to download diagnostic trouble codes from your car computer. | Source

3. P0105 and Other MAP Trouble Codes

Sometimes, a malfunction in the MAP sensor or its circuit will trigger the check engine light (CEL).

Scanning the computer, you may find a P010X series of codes stored in memory.

Here is a brief description of these codes:

  • P0105: MAP sensor circuit malfunction.
  • P0106: MAP sensor circuit, range or performance malfunction.
  • P0107: Circuit, low input.
  • P0108: MAP sensor circuit, high input.
  • P0109: MAP sensor circuit, intermittent failure.

Other related codes include P0068 and P0069.

You can find a more detailed description of these codes in your vehicle repair manual or by searching on-line.

Carefully read the description of the code you've found and what the potential fault resulted from this code.

Remember that even though the code points to the potential problem, the particular circuit or component involved may not be at fault. Instead, a related component may have triggered the code.

For example, in many applications a leaking vacuum hose or a bad throttle position sensor (TPS) may cause a trouble code that points to a faulty MAP sensor.

Troubleshooting the sensor is the only way to determine whether the sensor or part is actually bad.

On some models, you only need to remove a couple of screws to get to the sensor.
On some models, you only need to remove a couple of screws to get to the sensor. | Source

4. MAP Sensor Location

The MAP sensor is usually located in a few key places around the upper engine bay area.

  • Intake manifold. Under or near the throttle body; this is perhaps the most common place.
  • Inner fender.
  • Firewall.
  • Air cleaner assembly.
  • Under the dashboard.

The sensor may connect to the intake manifold with a vacuum hose or directly, by sitting on top of the intake manifold.

Caution: When Using a DMM

Always use a digital multimeter with a minimum 10 megaohms of impedance, to prevent damage to sensitive electronic and electrical devices in your vehicle.

Use a digital multimeter with at least 10 Megaohm impedance to troubleshoot the MAP sensor.
Use a digital multimeter with at least 10 Megaohm impedance to troubleshoot the MAP sensor. | Source

5. How to Test a MAP Sensor

When testing a MAP sensor, first make a preliminary check.

The sensor connects to the intake manifold with a rubber hose, depending on your particular application; otherwise it connects directly to intake.

When problems arise, it's more likely that the vacuum hose has failed. Within the engine compartment sensor and hose are exposed to high temperatures, potential contamination from oil and fuel, and vibration that can affect their operation.

Check the vacuum hose for:

  • kinks
  • loose connections
  • cracks
  • swelling
  • softening
  • hardening

Then, check the sensor's body for damage and make sure the electrical connection is tight, clean, and the wiring is good.

Compare your readings to specifications listed in your vehicle repair manual.
Compare your readings to specifications listed in your vehicle repair manual. | Source

6. Checking the MAP Sensor Reference Signal

The MAP sensor uses a three-wire connector. You need to identify the signal, reference, and ground wires using your vehicle repair manual.

Checking for reference voltage:

  1. Turn the ignition key to the On position but don't start the engine. This will allow the computer to supply a reference voltage to the MAP sensor.

  2. Set your multimeter to about 10V on the direct current (DCV) scale.

  3. Backprobe the reference wire at the connector. The readout should show 5 volts or close to it.

    • If your voltage is lower, visually inspect the connector and wire between the sensor and the PCM for damage. You may need to measure this voltage on the same wire but at the computer side.
      • If you still get a low voltage at the computer side, then you need to check the computer.
      • Otherwise, if the voltage rises to 5 volts, than there is a problem in the wire between the computer and sensor.
  4. Turn off the ignition key.

Checking for signal voltage:

  1. Unplug the sensor’s vacuum hose.

  2. Connect a hand-held vacuum pump to the sensor, but don’t apply vacuum to the sensor yet.

  3. Backprobe the signal on the electrical connector using the red DMM probe. Connect the black DMM probe to ground using any metal surface on the engine or the battery negative post.

  4. Turn the ignition switch to the On position, but don't start the engine.

  5. Your voltage reading should be between 4.6 and 5 volts.

  6. Apply 5 in-Hg of vacuum to the sensor. The readout should be about 3.75 volts.

  7. Now apply 20 in-Hg of vacuum to the sensor. The voltage should be about 1 volts.

Your readings may vary slightly, depending on altitude and current weather conditions.

NOTE: On some repair manuals, you're asked to check resistance while applying vacuum to the sensor. Follow the instructions in your particular manual and compare your results to listed specifications.

The following table shows the approximate MAP sensor return-signal voltage drop when a specific amount of vacuum is applied. Use these values as a general reference.

Also, watch the video towards the end of this post that gives you a visual reference about troubleshooting an analog MAP sensor using a DMM and a hand-held vacuum pump.

MAP Sensor Voltage Drop Reference Table

Vacuum
Voltage drop
5 in-Hg
0.7 to 1.0 Volts
10 in-Hg
1.3 to 1.9 Volts
15 in-Hg
2.0 to 2.8 Volts
20 in-Hg
3.0 to 3.8 Volts
You can use an oscilloscope or a DMM with a frequency function included to test a digital MAP sensor.
You can use an oscilloscope or a DMM with a frequency function included to test a digital MAP sensor. | Source

7. Testing a Digital MAP Sensor

If your vehicle uses a digital MAP sensor, instead of an analog one, you can also test it using a DMM that can measure frequency signals.

  1. First, set your multimeter to about 100 or 200 hertz.

  2. Unplug the vacuum hose form the sensor and plug in a hand-held vacuum pump to the sensor's vacuum port.

  3. Backprobe the signal and ground wires at the sensor electrical connector.

  4. Turn the ignition key to the On position but don't start the engine.

  5. Make a note of the voltage, duty cycle and frequency readings on your meter.

  6. Now, apply about 18 in-Hg of vacuum to the sensor, and note the voltage, duty cycle and frequency readings on your meter.

    • Your sensor should have about the same voltage and duty cycle readings in both tests.

    • Without vacuum applied, the sensor should have about 160 hertz.

    • With vacuum applied, the sensor should drop to about 100 hertz.

Consult your vehicle repair manual for specifications.

On some models, you may need a Torx screwdriver or bit to remove the MAP sensor.
On some models, you may need a Torx screwdriver or bit to remove the MAP sensor. | Source

8. MAP Sensor Replacement

Replacing a MAP sensor is a straightforward operation. Sometimes the sensor is readily accessible and you can replace it in about 5 minutes or less; other times, you may need to remove one or more accessories to gain access to it.

Regardless, the following procedure will help you replace the sensor. If the sensor in your vehicle uses a vacuum hose, it's a good idea to replace it along with the sensor.

  1. First, locate the sensor. You may find it:

    • around the top of the intake manifold
    • near the firewall
    • sitting next to the throttle body or under it
    • mounted on the tower on the well

    Consult your vehicle repair manual, if necessary,

  2. Disconnect the negative battery cable and secure the cable away from the post.

  3. Depending on the location of the sensor, you may need to remove one or more bolts or Torx screws.

  4. Unplug the sensor electrical connector. The connector may be securely locked. If so, depress the locking tab and then unplug the connector.

  5. Detach the vacuum hose from the sensor, if it has one.

  6. Detach the vacuum hose from the other end.

  7. Use the old vacuum hose as a guide to trim the new one to proper length, if necessary.

  8. Connect the new hose to the fitting on the intake manifold side, and the other end to the new MAP sensor.

  9. Plug in the sensor electrical connector. Make sure the connector locks to the sensor.

  10. Mount the new sensor in place.

  11. Connect the negative battery cable to the battery post.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

  • I have a 2004 Buick LeSabre. If my sensor has a crack in it, does it necessarily mean it's bad? I ask because I just had to replace head gaskets. Is it due to the sensor?

    You can test the sensor to make sure it's operating properly. If it already has a crack, it's better to replace it. The sensor only measures vacuum or intake pressure and it won't cause damage to the head gaskets.

  • I have a 06 Altima that keeps giving a P0420 code for the oxygen sensor. I replaced both sensors and crank position sensor, which we had a code. The crank code went away, the oxygen sensor will not. I previously replaced catalytic converter 2 times, then both oxygen sensors and code is still on for the 02 sensor. What could the P0420 code mean?

    Code P0420 points to the downstream oxygen sensor. According to the code, the sensor is reading too much oxygen in the exhaust stream. There could be a leak in the exhaust system, misfire, the faulty fuel injector (too much fuel), faulty fuel pressure regulator (increased pressure), or even a fault in the downstream oxygen sensor circuit.

  • We have a 08 Charger with a Hemi. We have replaced the fuel pump, throttle body, crankshaft sensor, and peddle assembly. What else can we do?

    If you are having problems with fuel delivery or spark have the fuel or ignition system tested. It’s not a good idea to replace components without troubleshooting the specific components.

    This other post can help you start troubleshooting the fuel system:

    https://axleaddict.com/auto-repair/How-to-Test-a-F...

    Check you have a good spark. If you haven’t already, check for trouble codes, even if the check engine light is not coming on. There could be pending codes that can help you figure out what component/system is giving you problems.

  • My 2002 Town and Country is showing a misfire in cylinders one and four. It runs rough at idle, backfires under load or acceleration, surges when trying to hold at 4000 RPM and park. Is the MAP at fault for my Town and Country's cylinder issues, or is something else going on?

    There could be several reasons for a misfire. Your misfire is located on the 1 and 4 cylinders; this can make it easier to locate the fault. Check out this other post. it may help you find the source of the misfire:

    https://axleaddict.com/auto-repair/Engine-Misfires...

  • I have a 2004 Dodge Dakota. Engine light came on. Truck started to kind of spit and sputter. O2 codes came up along with a heat code. I replaced all 4 sensors. It ran great. Now 2 months later it's doing the same thing. No one can figure it out. I have been told the computer may be bad. Any ideas?

    The engine might be running in open loop because of the code and running rich. Check for foul spark plugs that might be causing misfires. If you still have the old ones, check those sensors for carbon buildup. There can be a problem with the catalyst that might be affecting one or more O2 sensors. Also, the problem could be in the circuit to the heating element or the sensor themselves.

© 2018 Dan Ferrell

Comments

    0 of 8192 characters used
    Post Comment
    • Dan Ferrell profile imageAUTHOR

      Dan Ferrell 

      3 months ago

      The code is for the model with the 6 Cylinders V 3.0L engine. If you have the 4 cylinder engine, check the air cleaner assembly. There could be a leak that is upsetting the air-fuel mixture.

    • profile image

      Skylar 

      3 months ago

      I have a 1992 toyota camry i keep getting code p0104 for my check engine light but i do not have a maf sensor. My car idles fine when cold as soon as it warms up it idles rough drives decent sometimes it has a gas smell and poor fuel economy and when i stop at a light my cars rpms is about 400rpm

    • Dan Ferrell profile imageAUTHOR

      Dan Ferrell 

      3 months ago

    • profile image

      Shawn Brown 

      3 months ago

      I have a Cadillac Escalade esv 03 and i keep getting a code P0300 i put new plug in wire can someone help me with my problem it's been down for 5 week please help.

    • profile image

      Mukabya Samuel 

      9 months ago

      Thanks

    • Dan Ferrell profile imageAUTHOR

      Dan Ferrell 

      10 months ago

      The best way to know is to test the sensor(s). You may want to check the procedure in the vehicle repair manual for your particular model. If you don't have the manual, check the reference section of you local public library. Also, scan the computer memory for trouble codes using a code reader. Hope this helps.

    • profile image

      Jmontman 

      10 months ago

      I have a 1989 Bronco 2 with the 2.9 v6. I’m getting a skip or sputtering every few seconds. But it’s not bad on certain days. Depending on the weather it either runs smooth or rough. This is what makes me think of the MAP sensor. I’m pretty sure that I need o2 sensors but after watching a few videos I’m wondering if I should just replace all the sensors. Any opinions on a solution?

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, axleaddict.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://axleaddict.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)