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Summary
  • The powertrain control module uses the MAP sensor to sense engine load on speed-density-type fuel injection systems.
  • MAP sensor cleaning is a fairly straightforward process that requires simple items like a MAP sensor cleaner, soft rag, and brush.
  • A failing or dirty MAP sensor can cause your vehicle to exhibit symptoms like misfiring, stalling, and rough running.

Vehicle maintenance is more than a car wash, tire change, or an oil change. For dedicated drivers, maintenance means dealing with the nitty-gritty, including popping the hood and cleaning every dirty part they can find.

The MAP sensor is often overlooked during regular maintenance checks, but it’s a part that often gets contaminated with dirt, which is why you need to clean it regularly.

Here’s a simple guide on how you can clean it the right way.

MAP Sensor Basics

Diving into the basic functions of the manifold absolute pressure (MAP) sensor will help you understand why it’s important to clean it regularly and replace it when needed.

The powertrain control module uses the MAP sensor to sense engine load on speed-density-type fuel injection systems.

, The Right Way to Clean the MAP Sensor

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Low vacuum means more load on the engine. With a vacuum gauge connected to the engine you can watch the reading change and compare it to the MAP readings on your scan tool datastream to see if the actual gauge reading agrees with the MAP sensor. Vacuum is measured in inches of mercury, (Hg) and you can’t have more than 30 inches of vacuum no matter what you do.

Determining the engine load is crucial to determining the right amount of fuel the engine needs. The MAP sensor is also used as a backup sensor to the mass air flow (MAF) sensor on some engines and is also the input some systems use for EGR flow feedback. Chryslers and Jeeps used MAP sensors and stayed away from MAF sensor systems for many years.

The MAP sensor also doubles as a BARO sensor when the key is first switched on, determining the altitude to adjust fuel delivery and spark timing accordingly.

It also plays a crucial role in diagnosing issues related to the exhaust gas recirculation (EGR) system. If the MAP sensor doesn’t react to the specified drop in the manifold vacuum, an EGR flow rate trouble code may be set.

Can a MAP Sensor Be Cleaned?

Absolutely. MAP sensor cleaning is a fairly straightforward process, and it only takes a few items to get the job done, including the following:

  • Electric parts cleaner (preferably a manufacturer-recommended MAP sensor cleaner)
  • Soft rag or paper towel
  • Brush

Experts recommend cleaning the MAP sensor every 30,000 to 50,000 miles as part of your vehicle’s regular maintenance.

Deciding Whether the MAP Sensor Needs Cleaning

If your vehicle accelerates poorly and your fuel mileage is poor, and you notice slow response to MAP pressure readings when changing throttle angle and watching the sensor using a scan tool data stream display or when using a meter (while driving), there could be base engine issues. But before you pursue more expensive diagnostic paths, it might pay to start with the simple and easy.

First, inspect the MAP sensor’s electrical contacts. You might not see anything, but use some electrical contact cleaner anyway and retest.

If there is no change, remove the sensor from the manifold or disconnect the hose and check to make sure there is no PCV sludge clogging the port where the MAP sensor reads manifold pressure. If there is, carefully clean it out and retest.

If there is still no change in the results, substitute a known good MAP sensor. Once you’ve eliminated the MAP sensor and its circuit, your problem may be somewhere else.

If your vehicle accelerates poorly and your fuel mileage is poor, and you notice slow response to MAP pressure readings when changing throttle angle and watching the sensor using a scan tool data stream display or when using a meter (while driving), there could be base engine issues.

– Richard McCuistian, ASE Certified Master Automobile Technician

How to Remove the MAP Sensor

map sensor removal for cleaning
Removing the MAP sensor properly is crucial when you’re attempting to clean the sensor thoroughly.

Removing the MAP sensor properly is crucial when you’re attempting to clean the sensor thoroughly.

First things first, turn off the ignition and disconnect the battery to avoid electrical issues from popping up during the process.

In most cases, the MAP sensor can be found on or near the intake manifold, which is on the right side of the engine. The sensor should be behind the throttle body and attached to an electrical connector.

For some vehicles, the MAP sensor might be hidden behind the vacuum hose, which you’ll need to remove to get a better view of the sensor.

Unhook the vacuum line from the MAP sensor, and unscrew the bolts or screws that are mounting the sensor to your vehicle. Unhook the electrical connector, and you should be able to pry out the MAP sensor from its place.

How to Clean the MAP Sensor

When cleaning the MAP sensor, it’s important to hold it face down to prevent debris from contaminating the area.

Only use a manufacturer-recommended MAP sensor cleaner when cleaning the inside and outside parts of the sensor.

Use a soft rag or paper towel to wipe the housing, and proceed with spraying the cleaner into the sensor port. Shake out the excess cleaning solution, and let the MAP sensor dry.

You can also use the same cleaner with a brush to clean the vacuum hose and intake manifold port.

Tech Tips When Cleaning the MAP Sensor

Cleaning the MAP sensor might seem like a simple task, but it’s extremely important to exercise caution when doing so. Make sure to wear durable gloves and safety glasses to protect your skin and eyes.

It’s also best to avoid physically touching the sensor and using compressed air, as it can be too harsh on the chip.

Stick to recommended cleaners for the MAP sensor. Avoid using carburetor and brake cleaners, as these can leave residue inside the sensor, compromising its operation.

Testing the MAP Sensor

Reinstalling the clean MAP sensor doesn’t mean it’ll work like it’s as good as new. Once you’ve returned the MAP sensor to its proper place, the next step is to test it out.

There are a couple of ways to test a MAP sensor: using a digital multimeter (DMM), scope, or scan tool.

Using a Digital Multimeter or Scope

To test the MAP sensor using a DMM or scope, use jumper wires, T-pins, or a breakout box to access the sensor’s wiring.

Turn the ignition off, and measure the voltage or frequency of the sensor output. Then, use a hand-operated vacuum pump to apply vacuum to the sensor.

You’ll know that the MAP sensor is working as it should when it changes voltage or frequency in relation to the applied vacuum.

A stagnant signal or out-of-range values could mean that the sensor needs to be replaced.

Using a Scan Tool

A scan tool can help you determine the condition of the MAP sensor by monitoring the injector pulse width when vacuum is applied to the sensor.

Apply about 20 in. Hg of vacuum to the MAP sensor and start the engine. Observe the injector pulse width. If the engine is warm enough, the readings should range from 1.5 to 3.5 ms.

Slowly reduce the vacuum to the MAP sensor. The injector pulse width should increase because the low vacuum puts additional load on the engine.

Bad MAP Sensor Symptoms

A functioning MAP sensor can optimize your engine’s performance and fuel economy. Meanwhile, a failing one can cause your vehicle to exhibit symptoms like misfiring, stalling, and rough running.

Nobody wants to deal with a poor-performing vehicle. Aside from consuming too much fuel, you also risk damaging other parts if you continue to drive it around.

Heat and excessive vibrations can cause the MAP sensor to wear out faster than its intended service life. Contaminants like dirt and engine oil can affect the sensor as well.

MAP Sensor Replacement Cost

Cleaning a dirty MAP sensor can only do so much. If the sensor is too far gone, there’s no other solution but to replace it with a new one.

You can expect to pay anywhere between $110 and $130 for a new MAP sensor. Labor fees for the installation process can cost around $38 to $48.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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John

An interesting and thorough article about how MAP Sensors work, the importance of their correct input to a properly running engine, how to clean and maintain the MAP sensor, and methods to diagnose and test if a sensor is good, bad or starting to fail and if it needs to be replaced.

Another good article reviewed by Richard McCuistian.

Now, I want to buy some MAP Cleaner and clean my car’s sensor for preventative maintenance and will continue to do so in the future. It’s certainly an inexpensive procedure and easy enough for a week-end mechanic. Thanks for the informative article.

John

Notes to the writer(s):

Using a Digital Multimeter or Scope

“To test the MAP sensor using a DMM or scope, use jumper wires, T-pins, or a breakout box to access the sensor’s wiring.”

If the term “scope” if referring to an Oscilloscope, it would be helpful to clarify that, since there is also an Endo-“Scope” often used in diagnosing car problems. Endoscopes are relatively inexpensive and many DIYers may own one. Oscilloscopes, on the other hand are expensive and require training to use. Professional mechanics may own one, but I doubt many DIYers own or even know how to use one. That method of testing is best left for a professional mechanic – not a DIYer.

“Turn the ignition off, and measure the voltage or frequency of the sensor output.”

Question: If the engine is turned OFF. Why would there be any voltage or frequency generated by a non-running engine? Shouldn’t there be no power to the sensor?

Last edited 1 month ago by John

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