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9 Symptoms Of A Bad Map Sensor

Author: Apogeeweb
Date: 16 May 2022
cleaning map sensor



Ⅰ What is a MAP Sensor?

Ⅱ What Does A MAP Sensor Do?

Ⅲ How Does A MAP Sensor Work?

Ⅳ MAP Sensor Function

Ⅴ 9 MAP Sensor Symptoms

Ⅵ How to Replace MAP Sensor

Ⅶ How to Solve MAP Sensor Problems

Ⅷ How To Clean MAP Sensors

Ⅸ MAP Sensor Vs. MAF Sensor

Ⅹ MAP Sensor Replacement Cost


1. How do I upgrade my map sensor?

2. Will a map sensor throw a code?

3. Can you drive with a bad map sensor?

4. Can a map sensor cause misfire?

5. Can a bad map sensor cause car not to start?

6. Will a map sensor cause a misfire?

7. How long can you drive with a bad map sensor?

8. How to troubleshoot a map sensor?

9. What is the average lifespan of a map sensor?

10. Can the MAP sensor activate the limp mode?


The powertrain control module (PCM) uses the manifold absolute pressure (MAP) sensor to monitor intake manifold pressure. Because pressure is inversely related to vacuum, the PCM may use the MAP sensor input to calculate engine vacuum and load. The MAP sensor is also used to determine barometric pressure in some circumstances. The PCM will utilize this information to calculate one or more of the following: fuel control, ignition timing, and EGR operation, depending on the application.

In this essay, I'd like to introduce you to the Manifold Absolute Pressure (MAP) sensor's underutilized diagnostic power.

How to Test a MAF or MAP Sensor With a Multimeter - Plus an Operations Guide

 What is a MAP Sensor?

MAP is an abbreviation for Manifold Absolute Pressure. This MAP sensor detects the volume of air entering the engine by measuring the amount of air in the intake manifold. The ECU then uses this air measurement to manage the amount of gasoline injected into the engine and modify ignition timing, both of which are critical for your engine to function properly.

 What Does A MAP Sensor Do?

Manifold Pressure Sensor, as the name implies, calculates the pressure inside the manifold. In detail, the fundamental function of this sensor is to give the PCM various pressure readings. The Powertrain Control Module then utilizes this information to decide the amount of fuel injected into the cylinders. Furthermore, it aids in the management of ignition timing, which further prevents spark and so protects the engine from damage.


 How Does A MAP Sensor Work


How Manifold Absolute Pressure (MAP) Sensor Works

The car's MAP sensor is one of the most crucial sections of the vehicle, and its perfect operation is required for the vehicle to function normally.

The manifold absolute pressure sensor operates by changing the electrical resistance and output voltage value due to changes in intake air pressure applied to the silicon chip.

To compute intake air volume, the manifold absolute pressure sensor monitors the intake manifold pressure. Inside the MAP sensor is a sealed vacuum chamber with either a perfect vacuum or a calibrated pressure, with the intake manifold air pressure to be measured on the opposite side.

A Piezoresistive resistance sensor, which is a tiny flexible silicon chip, is used in the sensor. The silicon chip deflects in response to the intake air pressure, causing a change in resistance as well as output voltage, which is relayed to the car's electronic control unit (ECU) to modify fuel based on the air.

When the engine is turned on but not yet started, atmospheric pressure exists inside the intake manifold, which aids in estimating air density.

When the engine is started, the pressure inside the intake manifold decreases, and a vacuum is created, and when the driver presses the accelerator pedal, more air enters the manifold, generating high pressure inside the intake manifold.

Because of the high air pressure, the silicon chip flexes upward, causing a change in resistance, and its internal circuitry transforms the change in current into the output voltage value. As the pressure in the intake manifold raises, the resistance of the resistive element falls, and the voltage signal rises.

Similarly, when the driver takes his or her foot off the accelerator, less air enters and causes low pressure in the intake manifold, allowing the silicon chip to return to its idle state. As a result, you change the silicon chip's resistance and output voltage.

The ECU uses this voltage change to compute the stoichiometrically correct air-fuel ratio for the car's engine.

 MAP Sensor Function

Function Of MAP Sensor


The manifold absolute pressure's function is to send the instantaneous pressure of the intake manifold to the car's electronic control unit (ECU).

The data produced by the manifold absolute pressure sensor is utilized by the car's ECU to determine the absolute amount of fuel that the engine may use while leaving no surplus oxygen or unburned fuel.

This allows the car's internal combustion engine to function properly with no harmful fuel while also ensuring the car's steady functioning with the use of precise stoichiometric calculations to ensure appropriate combustion. It also assists the engine in determining ignition timing by providing total mass air flow information at all times.

 9 MAP Sensor Symptoms

Always begin troubleshooting by connecting the engine to a diagnostic reader. This can save you a significant amount of time by providing you with an error number that will send you in the appropriate direction. In my opinion, this is the easiest way to diagnose an engine problem and will often bring you right to a defective sensor.


When troubleshooting an engine performance issue, checking the ECU for error codes can save you a lot of time.

If you rely on engine performance symptoms, keep in mind that they can be caused by problems with other sections of the engine. Defective fuel injectors, unclean fuel filters, a faulty MAF sensor, vacuum leaks, and fuel pump issues can all show as difficult to start engines or engines with limited power, especially when accelerating.

A defective MAP sensor can cause intermittent problems, and cleaning the sensor can occasionally remedy the problem. It can be difficult to establish the exact source of the problem, therefore it may be important to seek expert advice and monitor engine performance using real-time diagnostics.

Here are some general performance related map sensor symptoms that could indicate a damaged MAP sensor:

1. Check Engine Light 


​It should come as no surprise that many fault codes are associated with the MAP sensor. The self-diagnostics routines in ECUs have been refined over time to pinpoint practically any imaginable MAP issue, such as ground line loss, inconsistent signal, reference voltage, broken sensor, and so on. However, keep in mind that the sensor's unique properties make it susceptible to false positives, especially when a vacuum leak is present.

2. Decreased Engine Performance 

Depending on the ECU programming and emergency mode techniques, you may suffer varying degrees of power loss during acceleration. In general, the ECU can no longer detect the engine's load and must thus extrapolate information from the rest of its sensors to calculate an approximate figure. That value is then used, and the outcomes are corrected using the oxygen sensor closed-loop feedback.

3. Hard Starting 

Once again, this is heavily conditioned to the software of the ECU. It's not rare to discover cars with a no-start problem when the MAP isn't communicating with the ECU, but the opposite is also true. Even if the MAP is unplugged or malfunctioning, many vehicles will start without a hitch. There are limitless variants to the aforementioned extreme conditions, as well as a slew of other factors that could prevent the engine from starting. Keep all of this in mind if you encounter a MAP issue.

4. Poor Fuel Economy 

Without MAP's critical information, the ECU will struggle to regulate the air-fuel ratio. As a direct result, expect a considerable loss in fuel economy.

5. Rough Idle 


The fuel mixture will be constantly altering between lean and rich as part of the ECU's compensating procedure. Some vehicles may experience a harsh idle as a result of this difference.

It is impossible to forecast how choppy the idle will be due to other engine issues that may be present in addition to the MAP failure. Idle performance can also be affected by a blocked air filter, a limited exhaust system, or a vacuum leak. Unfortunately, without the MAP signal, the ECU will be unable to compensate for such a confluence of problems.

6. Engine Misfires 


Engine misfires are a side effect of MAP failure and constant air-fuel ratio fluctuations.

Engine misfires should be addressed seriously because they might cause engine damage. If you experience noticeable misfires and/or exhaust backfiring, it is strongly advised that you cease driving the vehicle until it can be inspected.

7. Gas Smell Coming From The Exhaust Pipe 

Another immediate result of a low MAP is a gas odor emanating from the exhaust. Fuel particles streaming through the exhaust system is a common issue when combustion does not complete in the chamber.

This symptom should not be ignored because it is more delicate than you may assume. Aside from the stench and possibly smoke from the exhaust, the catalytic converters may be irreversibly damaged since liquid particles such as unburned fuel are extremely damaging to catalytic converters.

8. Barometric Issues 

Unless you're on a long trip with notable barometric fluctuations, this symptom may be difficult to detect.

For example, if you start the engine at the bottom of a mountain and begin driving uphill, you will notice a progressive loss of power due to the ECU's inability to compensate for variations in barometric pressure.

9. Failed Emission Tests 


Last but not least, your car will fail any emission tests under these conditions. If you live in a location with stringent smog rules, a malfunctioning MAP might get you in hot water. Keep this in mind if you intend to drive your automobile while the MAP problem is present.

 How to Replace MAP Sensor

Many fuel-injected automobiles, particularly those that are older or have turbocharged engines, use a MAP (or manifold absolute pressure) sensor to monitor how much air is entering the engine. This information is used by the computer to calculate how much gas the fuel injectors need to give to the engine for optimal combustion. If your automobile has been difficult to start, has an inconsistent idle, has low fuel economy, or has stalled, the cause could be a faulty MAP sensor. A faulty MAP sensor may also trigger the "Check Engine" light.

The MAP sensor is usually accessible and simple to remove and replace. It is frequently situated near the engine's intake manifold and should have an electrical as well as a mechanism to measure the air pressure in the intake, either directly to the manifold or through a vacuum hose. To begin removing the old sensor, unplug the negative battery cable. This prevents the automobile from being harmed when the sensor is removed and also resets the vehicle's computer and trouble codes. Remove the sensor's connectors and any nuts or bolts that are holding it in place. Finally, take the sensor out of the engine.

 How to Solve MAP Sensor Problems

As we all know, a functioning MAP sensor is an essential component of car maintenance. After you have verified the following elements, you will be able to determine whether it is only a simple fix or whether you require a replacement.

Electrical You should begin by inspecting the wire and the connector. This connector should be securely linked, with clean, straight pins. When there is corrosion or bent pins, the MAP sensor may encounter a problem. At the same time, the ECM and MAP sensor connecting wires must be in good condition. Chaffing might potentially generate a short circuit, and breakage would result in open circuits.
Hose A hose connects the intake manifold to a MAP sensor. Check that the MAP sensor's connection to the hose is secure. Check to see if the port is clean of debris or carbon deposits. This dirt could clog the hose and cause the MAP sensor to read incorrectly.
Sensor If the sensor is properly connected, both electrically and to the intake manifold, utilize a scan tool or voltage meter with a vacuum gun to verify the MAP sensor output. Using the chart, you must measure the voltage against a full vacuum or no vacuum. If the chart does not match the MAP sensor data, the sensor should be replaced.

 How To Clean MAP Sensors

There are only a few more steps to cleaning MAP sensors:

  1. Find and remove the MAP sensorfrom the intake manifold (if you can't find it, consult a repair manual). When removing it, take care not to drop it down the rear of the engine or destroy the wiring or connector. If the vehicle is older, the wiring may become brittle and lose its flexibility.
  2. Inspect the sensor for cranks in the casing, scorch marks, or connecting issues. If everything appears to be in order, it may be worth cleaning.
  3. A excellent quality MAP sensor spray cleaner is required to clean the sensor. If you can't find one, a mass airflow cleaner will suffice.
  4. Spray the cleanser into the sensor's nozzle ( the part that pushes into the manifold). Don't be tempted to stick a screwdriver or anything else into there; instead, let the cleaner do the job.
  5. After a few minutes, spray some additional cleaner into the sensor and gently shake it with the nozzle down to clear any dirt.
  6. You may need to repeat this process several times until it is clean.
  7. Cleaning the inlet manifold is also a good idea. If you have the ability, the easiest method to accomplish this is to remove it from the automobile and thoroughly clean it.
  8. If you can't get it out of the car, apply some MAP cleaning on a clean rag and clean around the MAP sensor mounting hole. If it's toward the back of the engine, you may not be able to reach it; in this case, you'll have to remove the manifold to clean it.
  9. Once everything is clean and dry, replace the MAP sensor, clear any engine codes, and test the car to check if the fault codes reoccur.

If cleaning it does not work, then a MAP sensor cannot be repaired. Engine sensors tend to lose sensitivity over time. Typically, the best method is to simply replace the sensor that is generating error signals.

In rare circumstances, simply replacing the MAP sensor will not resolve the issue. The mistake could be caused by a leak somewhere in the air intake system.

To determine the source of the problem, you may need to inspect the vacuum hoses, air filter, or EGR valve. For further details, see my post on error code P0106 and how to detect a broken EGR valve.

Here's a quick rundown of what's involved:


Vacuum hoses: Visually inspect all vacuum lines, including the MAP sensor, PCV, brake vacuum booster, fuel pressure regulator, and so on. Also, inspect the air intake pipe for signs of deterioration or leaks. When the MAP/BARO sensor is mounted directly on the intake manifold, it is sealed with a rubber o-ring. Examine its condition and replace it if needed.

Exhaust Gas Recirculation valve inspection: inspect the EGR valve's exterior, tubing, and connections thoroughly. Examine the EGR gasket and connections for suspected exhaust leaks. If necessary, replace the gasket and/or the EGR valve.

 MAP Sensor Vs. MAF Sensor

Today, every EFI vehicle has either a MAF sensor (mass air flow) or a MAP sensor ( manifold absolute pressure). Some vehicles, such as the Mitsubishi Evo X, have both a MAF and a MAP sensor. So, what exactly do these sensors do and how do they differ?

MAP Sensor

A map sensor is a sensor that is mounted in or close to the intake manifold. It is a pressure sensor that monitors the pressure in the manifold. On a normally aspirated engine, this sensor will detect the negative pressure found in the intake manifold, which is referred to as a vacuum. If the vehicle has Forced Induction, this sensor will be in charge of detecting not just the vacuum but also the real positive pressure in the manifold.

Because this sensor must measure both vacuum and pressure, it is available in a variety of sizes. These ranges are frequently expressed in the unit of Bar rather than PSI. The metric unit for pressure is the bar, while the standard unit is the PSI. When selecting a MAP sensor, select one that is appropriate for the quantity of vacuum and pressure that your specific motor will experience.

MAF Sensor

While there are numerous types of MAF sensors, let us concentrate on what they are. A MAF sensor, as the name implies, is a device that detects mass airflow. It monitors the mass of air passing through the sensor and sends the actual flow of air to the ECU. When dealing with and tuning a MAF sensor, it is common for the computer to interpret the MAF data to display an actual load value rather than a figure in CFM of flow. As a result, MAF sensors can be more difficult to adjust based on the ECU's interpretation of a given airflow.



While both sensors do the same thing, we could give each a plus.

MAP sensor
  1. Even if an intake pipe blows out or a vacuum hose leak occurs, the car will continue to run normally because the real manifold pressure will not change, leaving you stranded somewhere.
  2. The sensor reads the actual load, eliminating the need to assume what load level the engine is sensing.
MAF sensor
  1. Even at low air flow levels, the quantity of CFM entering the motor is VERY precise. As a result, MAF sensors tend to achieve higher MPGs (miles per gallon).
  2. Most have an AIT (Air Intake Temperature) sensor built-in, allowing you to monitor your actual air intake temps at the sensor.

 MAP Sensor Replacement Cost

If you've determined that your MAP sensor has failed, don't worry; replacing the sensor should be simple and inexpensive. In fact, most people could definitely handle this one themselves and save a lot of money.

The MAP sensor is frequently located in an easily accessible location, such as on or near the intake manifold. The sensor will cost you between $30 and $200, depending on your car and if you utilize OEM or aftermarket parts.

If you go to a mechanic or a dealership to have the MAP sensor updated, expect to pay an additional $40 to $60 in labor. Even though replacing should just take a few minutes, most establishments impose a minimum labor charge. In most circumstances, DIY replacement is the best solution.

A vacuum hose is sometimes used to connect MAP sensors to the intake manifold. If this hose has a vacuum leak, replacing it for less than $10 may be enough to repair the problem.

For information on how to repair a MAP sensor on your specific car, see a factory-style manual (such as Haynes or Chilton).


1. How do I upgrade my map sensor?

When a higher-rated sensor is fitted, the plug may be different than the standard sensor. That is why we developed our plug-and-play MAP adapters (see below). Simply install the new sensor using an off-the-shelf bracket from a firm like IAG, connect our adaptor to the stock MAP socket, then plug the other end into your new MAP sensor. Once everything is in place, we recommend tuning the car to ensure the new sensor is properly calibrated.

2. Will a map sensor throw a code?

It is acceptable to check up codes first because failed MAP sensors will not issue a code until they have entirely died.

3. Can you drive with a bad map sensor?

If your car's MAP sensor is damaged, it can possibly be replaced. However, this does not imply that you should. If you detect a defective MAP sensor, it can cause a broad range of engine performance issues, including your car stalling. Furthermore, a defective MAP sensor may cause harm to other automotive components.

4. Can a map sensor cause misfire?

If the onboard map sensor produces a false high-pressure value, the engine will tremble. If that reading results in a misleading high-pressure measurement, your engine will respond by adding fuel to the fuel filter. Because this mixture is likely to clog the spark plugs, the cylinder will not burn.

5. Can a bad map sensor cause car not to start?

Typical MAP sensor failure symptoms A faulty MAP sensor may impair fuel supply and ignition timing. Depending on the type of vehicle, the following performance issues are thought to arise. The fuel economy is subpar. You won't see it begin.

6. Will a map sensor cause a misfire?

A malfunction will arise from a malfunction in the engine's combustion that creates a malfunction in the cylinder. A faulty spark or air-fuel mixture could be to blame. There is a chance that your air-fuel mixture will deteriorate to the point where you will have misfires as a result of a MAP sensor.

7. How long can you drive with a bad map sensor?

With a faulty MAP sensor, you can travel up to 500 miles. This does not, however, imply that you should drive. If your symptoms have worsened, you should not drive even one mile. A faulty MAP sensor can shorten the life of your engine by causing knocking and misfiring.

8. How to troubleshoot a map sensor?

To troubleshoot a bad MAP sensor, look for the indicators listed above in detail. A smart first step is to utilize an OBD2 scanner to determine whether the MAP sensor has failed. If you run it for error codes, you'll know which sensor is faulty.

9. What is the average lifespan of a map sensor?

All sensors, including the MAP sensor, are built to last the life of your engine. Unfortunately, MAP sensors typically fail after 70,000 miles. If related issues are not addressed, it may fail much sooner.

10. Can the MAP sensor activate the limp mode?

Yes, the MAP sensor is an important component of your vehicle's electrical system. If it fails, the car immediately enters limp mode to safeguard other systems and components from additional harm.

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