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Symptoms Of A Bad MAP Sensor – What You Need To Know!

Symptoms Of A Bad MAP Sensor

In many modern engines, the engine control module calculates the amount of airflow in your vehicle. The engine control module does this by using a mass airflow or manifold absolute pressure sensor, also known as the MAP sensor. In certain luxury and high-powered cars, turbocharged engines can use both. However, in most vehicles, you will either find a MAP or MAF sensor. 

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This MAP Sensor is crucial to keeping your engine running smoothly and safely. If you notice any symptoms of a bad MAP SEnsor, then you need to get the problem fixed right away to prevent any severe issues. The ECM uses the MAP Sensor data to run calculations referring to the fuel, spark timing, and pressure, affecting engine performance. 

What is the MAP sensor?


Engines that use the MAP sensor are generally fuel injected. This means that these engines introduce fuel in the internal combustion engine by means of an injector. The manifold’s absolute pressure sensor, which analyzes the fluid’s applied force on a surface, provides the manifold pressure info directly to the engine’s electronic control unit. 


  • Electronic Control Unit



The electronic control unit is an embedded system in automotive electronics that controls multiple electrical systems and subsystems. The engine control unit controls a series of actuators on an internal combustion engine to ensure the best engine performance. It reads values from sensors, like the MAP sensor, and interprets the data using multidimensional performance maps, and adjusts the actuators. 


  • Mass Airflow Sensor



A fuel-injected engine might also use a mass airflow sensor to determine the type of intake airflow and the pressure. The mass airflow sensor, or the MAF sensor, determines the airflow rate that enters the fuel-injected internal combustion engine. The naturally aspirated engine uses one or the other.


  • OBD-II 



A forced induction engine uses both sensors, utilizing the MAF and MAP sensors. The MAF sensor determines the mass airflow rate on the charge pipe, and the MAP sensor goes to the intake section. 


MAP sensor data is converted into air mass data by utilizing technology from an IAT Sensor using the speed-density method. This MAP sensor can be used in OBD-II applications to test the EGR valve for functionality. 

Signs of a Broken MAP Sensor

MAP sensors can fail for many reasons. Some of the most common symptoms of a bad MAP sensor includes the part getting clogged, getting filled with debris, getting contaminated, or getting damaged. Sometimes, the engine heat can cause excess friction and generate too much heat for the electronic components. The damage of the vacuum lines’ electronics can lead to clear symptoms of a bad map sensor. 


If the MAP sensor becomes damaged or breaks down over time, the engine control module can’t calculate the correct engine load. Without the engine control module able to determine this data, the air to fuel ratio will become too rich. If the air and fuel mixture becomes too rich, this means that there is too much fuel. If the mixture has not enough fuel, this means it is too lean, and there is not enough fuel. Either of these fuel mixtures can be symptoms of a bad map sensor. 


So, what is the best way to know that your MAP sensor is going bad or becoming damaged? We have narrowed down the key problems to look out for. 


  • Poor Fuel Economy



If your electronic control module is reading very low vacuum or no vacuum, then the ECM is guessing that the engine is at a high load, and ends up putting more fuel into the system and sparking the timing in too soon. The early spark timing can lead to higher fuel consumption, which results in a lower fuel economy and possible multiple explosions or small detonations.


There are many reasons that you might have a poor or reduced fuel economy in your car. This fuel economy issue can also turn on your check engine light, alerting the driver to a bad map sensor’s symptoms. The causes of a reduced fuel economy are sluggish o2 sensors, defective coolant sensors, damaged engine thermostat, engine misfiring, intake manifold for EGR able leaks, and worn spark plugs. 


  • Lack of Power


Suppose the electronic control module is reading that there is a high vacuum, the opposite problem of what we previously mentioned. In that case, this assumes that the engine load is very low and prevents the spark timing. The fuel consumption will lower, which is good for the fuel economy, but this could backfire – if too little fuel is consumed, then the engine might not have enough power for the basic functions, like accelerating and passing. 


  • Failed Emissions Inspection


Since the fuel injection does not directly relate to an engine load, the broken MAP sensor that needs replacing can increase harmful emissions, generating higher hydrocarbon and carbon monoxide emissions. The emission inspection includes the confirmation or absence of the vehicle’s required emission control devices. The device required in the car is the gas cap, ensuring it is in good condition and fits properly. 


Emissions testing for each car determines the number of air pollutants coming from the exhaust of your vehicle. If your car does not pass the test, you need to repair your vehicle and do any replacement necessary. If you notice any bad map sensor symptoms, chances are you’ll have to do some repairs and replacements on your car to pass the emissions inspection. 


  • Rough Idle


Without enough fuel injection to provide the engine with oil, this can lead to rough idling and even cylinder misfiring. A rough idling engine is caused by various issues, like spark plugs or spark wires becoming damaged over time. A spark plug that is damaged due to prolonged use, or one that is installed incorrectly, can result in the fuel burning at the wrong time. 


If the fuel burns at an incorrect rate, you will notice a bad map sensor’s symptoms and your engine running rough. 


  • Hard Starting


A very rich or a mixture that is too lean makes the engine difficult to start and fire up, causing the engine to only start when your foot is on the accelerator. If you notice that it is taking longer to start your vehicle and there is a jerk when the car finally starts, there could be various reasons, like fouled spark plugs. Spark plugs are necessary for creating the spark to start the car – if these parts are damaged, you will also notice a bad map sensor’s symptoms. 


  • Hesitation or Stalling


When you start from a dead stop in your car, or you try to accelerate in your vehicle, stepping on the gas might not provide the same amount of power as if you had a working MAP sensor.


  • Check Engine Light


Depending on how old your vehicle is, the make, the model, and the vehicle, the MAP sensor diagnostic codes might range from simple faults to range faults, like correlation faults. A failing MAP sensor might give the ECM data incorrect or don’t make enough sense and turn on the check engine light

Bad MAP Sensor Parts


If you have finally figured out that the MAP sensor is a problem according to the previous symptoms, you know that an issue needs to be fixed to prevent symptoms of a bad map sensor. But where to start? Check these following components of the MAP sensor first to see where the problem originates. 


  • Electrical


Start by checking the connector and wiring of the MAP sensor, ensuring that the connector is secure and the pins are clean and straight. Any signs of corrosion, debris, or damage that is in the connection can harm the sensor. Similarly, the wiring between the ECM and the MAP sensor should be secure and intact. 


  • Hose


Some MAP sensors are connected to the intake manifold by a hose. Ensure that this house is connected, doesn’t contain any holes or leaks, and is intact.


  • Sensor


If the sensor is not connected in the right way or securely enough, both electrically and the intake manifold, use a scan tool or a meter to check the MAP sensor output. Check these output data against the measured voltage to see if your car is at a full vacuum. If the MAP sensor data does not match the chart, it is easy to determine that it needs to be replaced. 


By checking these parts of the MAP sensor first, you can make sure that you know where exactly the problem is originating from. Figuring out the origin can make the problem easier to diagnose and help you determine where you need to fix the issue so that the MAP sensor can continue working correctly. 

MAP Sensor Replacement Costs


To figure out how much you might pay for the MAP Sensor replacement for your specific vehicle, we have added a few of the most common and popular cars on the market today and the sample prices so you can get a feel for how much you might spend if you did end up taking your car to the local mechanic’s office. Let’s check it out.


On the lower end of the price spectrum, the Ford Fusion and the Ford Focus are the two least expensive options for a MAP sensor replacement. With labor costing between just $26 and $34, and the parts only cost around $93-$181, the total cost ranges from $119-$215 – which is not very expensive at all compared to more extensive and heavy-duty repairs like the engine and the transmission.


We have the Toyota cars – the Camry, Corolla, and the Nissan Altima on the higher end of the price range. Although this is more expensive, it is only a total of $8 more on the low end. Regardless of what kind of car you own, the MAP Sensor replacement will be a low-cost fix that will take very little time when compared to more extensive replacements. 


  • How to save money on the MAP sensor replacement



We know that everyone is looking to cut expenses in their life. Those looking to save money might want to try repairing this issue themselves instead of bringing it to a mechanic, which can get costly over time. In most cases, this replacement of the MAP sensor is not very complicated and can be done with some knowledge and tools. 


Just make sure that before you try this repair or replacement at your home or your office, you don’t mistakenly replace the incorrect part, which might be in working order, or miss a serious and severe issue.


  • When to get MAP Sensor Replacement



The most common sign and symptom that the MAP sensor is not working are that check engine light will be on in your car. Although this can happen for many reasons, it is crucial to figure out the real reason behind the check engine light is on.


The other reasons that the check engine light might turn on besides the MAP sensor is a faulty oxygen sensor, loose gas cap, faulty catalytic converter, faulty ignition coil, and bad spark plugs. In addition, a bad mass airflow sensor, non-compatible aftermarket alarm, and leaky vacuum hose on the EVAP system can lead to a damaged MAP sensor. 


As we know now, in most modern cars, the engine control module is in charge of the airflow in your vehicle. The engine control module uses the ever-important MAP sensor to determine the car’s pressure and airflow. In certain cars, you might also find a MAF sensor along with the MAP sensor. 


The MAP sensor is a key part of your engine and the ventilation system in your vehicle. However, sometimes you might notice symptoms of a bad MAP sensor. Noticing these signs can keep your engine and car running for a long period of time. 


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