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5 Symptoms Of A Bad MAP Sensor That You Should Watch Out!

symptoms of a bad map sensor

Credit: http://knowhow.napaonline.com/guide-map-sensor-cleaning/

It is notable that the Manifold Absolute Pressure (MAP) sensor is one of the most crucial components in the electronics system of your vehicle. Without it, your car won’t be able to perform well. A faulty MAP can result in different engine malfunctions.

Of course, troubleshooting these errors might cost you a lot of time and money. Therefore, it is your responsibility to know the symptoms of a bad MAP sensor. After all, the adage “prevention is better than cure” is always the unwritten golden rule of all modern vehicles. But before we elaborate these signs, let us discuss first what does a MAP sensor do.

What is a MAP Sensor?

What is a MAP Sensor?

Photo: http://liberty.eurekaboy.com/mapsensor.htm

As I mentioned above, the MAP sensor is a component that you have to install on newly manufactured vehicles. The function of this device is to gauge the pressure level that is present on the manifold. The measurement that it gets is correlational to the external barometric pressure.

The information that the MAP gets passes through the central computer of the vehicle or the electronic control unit. The data is being used by the engine computer to calculate and modify other factors that would balance the overall performance of the vehicle. One good example of this is the fuel injection rate. The MAP sensor also contributes to the optimization of the vehicle’s combustion.

Of course, you can expect that the vehicle will still run even the MAP sensor is faulty or malfunction. However, the caveat here is that your engine will suffer strongly from it. As a result, the emission level of the car would suddenly spike up.

This predicament is the reason why many car manufacturers and automobile technicians always recommend owners to check their MAP sensors regularly. Fixing the problem is quite cumbersome if the damage sustained by the sensor is too grave already. Therefore, you must know the standard indicators that would tell you that the MAP sensor of your vehicle needs immediate maintenance already.

Symptoms of a Bad MAP Sensor

Notably, the symptoms of a malfunctioning manifold pressure sensor are quite similar to the symptoms of faulty injectors. But for a more particular perspective, here are the things that you typically associate with a weakening MAP sensor.

Check Engine Light Warning

check engine warning light in car dashboard

The first and most apparent indicator that the MAP sensor of your car is going bad already is the flashing of “Check Engine” light. When this warning comes out, it means that the car’s computer has previously detected some erroneous reading from the sensor. Of course, a faulty MAP sensor is not the only culprit that can trigger the Check Engine light. Sometimes, it could be due to some leakages on the vacuum hose.

Because of this, it is proper that you should check the other components of your vehicle first before the MAP sensor. The reading might have spotted some other underlying issues that burden the overall performance of your car’s engine.

Increased Fuel Consumption

increased fuel consumption

Source: http://wonderfulengineering.com/increase-your-cars-fuel-mileage-using-these-simple-steps/

A faulty MAP sensor will give off unwarranted measurements of the high intake manifold pressure. That would be translated and processed by the computer as a form of necessity to increase the amount of fuel injected into the engine. Naturally, this would increase your fuel consumption. If you have noticed that have an increased frequency of going to gas stops lately, then you should check the performance of the MAP sensor already.

Aside from the excessive fuel needs of your vehicle, a bad MAP sensor can also elevate the volume of carbon monoxide and hydrocarbon emissions. That is a bad thing if you are an environmental activist. These two chemicals are among the primary perpetrators of the greenhouse effect.

Power Inefficiency

That is the direct opposite of the previous symptom that I mentioned. If the MAP sensor always gives a low reading on the intake manifold pressure, the car’s engine will decrease the fuel that transfers to the motor. Aside from the increase in your fueling frequency, you will notice that your car’s engine is not as reliable and efficient as it used to be.

If you lessen the fuel that transmits to the engine, there will be an increase in temperature in the combustion chamber. That would spike up the production of oxides of nitrogen (NOx). NOx, by the way, is among the significant perpetrators of smog.

Emission Test Failure

Power Inefficiency

Photo: http://www.anamotors.com/emission-test/

Perhaps, the most foolproof indicator of a bad MAP sensor is its inability to pass an emission test. That is nothing of a surprise already, as your tailpipe will tell that your engine is freaking out already. If there is a high level of carbon monoxide and hydrocarbon on your emission test, then your MAP sensor needs to be fixed as soon as possible.

Read more: http://www.autotap.com/problem3_failed_emissions.asp

Decrease in Engine Performance

If the MAP sensor does not transmit the correct information to the vehicle computer, it can result in the disruption of pressure balance. That can only result in the weakening of the engine. You can quickly notice this symptom whenever you accelerate or slow down your car. So, your engine will jerk whenever you crank the pedal. If your recent rides are rough, you should check your MAP sensor immediately.


Knowing the symptoms of a bad MAP sensor is essential to the stability and performance of your car’s engine. If your vehicle exhibits these signs, then it is the time that you do something about them.

Moreover, it would not hurt if you regularly visit any automotive services for quick checkups and diagnosis. In this way, you can ensure that your MAP sensor and other engine components will be in their top shape. These maintenance trips would cost you, but they are all worth it. After all, they can ensure the smoothness of every road trip that you have. Of course, your safety and convenience are on the line here, too.

Did you learn from this article? If you have any questions and suggestions, just feel free to ask me in the comment section below!

Steven K. Galloway