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Bad MAP Sensor Symptoms: How to Know When Your MAP Sensor is Failing!

Bad MAP Sensor Symptoms

A vehicle that experiences bad MAP sensor symptoms such as lack of power, has poor fuel economy, rough idling, hard starting, has an illuminating check engine light, stalling, or failing the emission inspections need to be checked immediately. The MAP sensor or the manifold absolute pressure sensor is used to provide fast manifold pressure data to the engine control unit or the ECU. It basically measures the air pressure in the intake manifold. The data received will be used to compute the air density and to find out the air mass flow rate of the engine that helps determine the needed fuel delivery for a flawless combustion. Without a good, working MAP sensor, your engine might not function properly. 

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There is also another kind of sensor that is used to measure the air flow which is the MAF or the mass air flow sensor. Vehicles that are equipped with turbocharged engines may use both sensors while vehicles with naturally-aspirated engines are usually equipped with either the MAF or the MAP sensor.  Today, we will focus on the MAP sensor, the bad MAP sensor symptoms, and everything you need to know!


MAP Sensor Symptoms: What is a MAP Sensor and How Does it Work?


To better understand why bad MAP sensor symptoms can occur we need to know what a MAP sensor is and how it works. Like mentioned earlier, the MAP or the manifold absolute pressure sensor measures the airflow in the manifold. It helps the ECU determine the appropriate air to fuel ratios since the data which the MAP sensor sends to it will be used to evaluate the air density.


This can help the ECU determine the engine’s air mass flow rate and decide the appropriate fuel metering to achieve a perfect combustion. Changing the MAP sensor’s information into air mass data can be done by using a method such as speed density which can be measured by using the engine speed and the air temperature. 


The manifold absolute pressure sensors are also being used to decide the fuel utilization, used to determine the fuel delivery, to adjust with the changing environment, and also to report the RPM variation. The MAP sensors are basically used to calculate the engine’s internal combustions and provide various pressure information to the ECU.


The MAP sensors play an important role to achieve a flawless combustion. It is for this reason that whenever you notice any bad MAP sensor symptoms, you need to act on it immediately and have it checked and repaired. 


MAP Sensor Symptoms: How can you tell if your MAP sensor is bad?


How will you know if you have a bad MAP sensor? You will know if you have a faulty one if you encounter any of the following bad MAP sensor symptoms.

  • Insufficient power.


One of the bad MAP sensor symptoms is having insufficient power. This can happen when the faulty MAP sensor measures low intake manifold pressure that indicates a low engine load to the ECU. When the ECU receives the reading, it will react by reducing the amount of fuel injected into the engine and it also tends to slow down the spark timing. 


You might notice an increased fuel economy which might be a good thing, however, it can result in your engine having insufficient power. It will not be as powerful as it was before. 

  • Failing emission inspections.


If you failed emission inspections or tests, it can be an indication of a faulty MAP sensor. With the ECU reducing the amount of fuel in the engine, the temperature in the combustion chamber will be increased, which also increases the amount of the nitrogen oxide or NOx. It is known to be one of the smog’s chemical components.  


A damaged MAP sensor can cause the vehicle to increase harmful emissions because the fuel injection does not correspond to the engine load. It can cause the ECU to reduce or increase the amount of fuel injected to the engine. While the insufficient fuel causes increased nitrogen oxide emissions, excessive fuel can cause increased hydrocarbon and carbon monoxide emissions.  


Tailpipe emissions that show high levels of carbon monoxide, hydrocarbons, and have high nitrogen oxide production will cause your vehicle to fail the emission tests and inspections. 

  • Poor fuel economy.


Excessive fuel consumption is also one of the faulty MAP sensor symptoms. This can happen when the faulty MAP sensors send high intake manifold pressure readings to the ECU indicating a high engine load. 


The ECU will respond to the readings by increasing the amount of fuel injected in the engine which can reduce your vehicle’s overall fuel economy. It can trigger poor fuel economy and can possibly cause detonation. 

  • Rough idling.


Since a faulty MAP sensor can send wrong data to the engine control unit of the vehicle, it can cause the ECU to send improper air to fuel ratio that can lead to excessive engine vibrations when idling. It could cause it to inject an insufficient amount of fuel in the engine leading to a fuel-starved engine that can result in rough idling or cylinder misfiring. 

  • Hesitation or stalling.


Hesitation or stalling is also one of the bad MAP sensor symptoms. If you suddenly step on the gas pedal or pull out in front of traffic and you feel that your car hesitates or stalls, it could mean that there is something wrong with the air to fuel mixture. The unexpected introduction of a lot of air makes it hard for the engine to keep up with the unanticipated load request. 

  • Hard starting.


Since a faulty MAP sensor can result in the ECU adjusting the air to fuel ratio, it can make it excessively rich or lean, making the engine hard to start. If you find it hard to start your engine or you can only start it when your foot is on the accelerator, it could be an indication that you have a bad MAP sensor. 

  • Check engine light.


Since the ECU always monitors all of the engine’s sensors when you drive your vehicle, if one of these sensors sends a reading that does not make sense or is out of its specified range, it will set off the check engine light on your dashboard. It is considered one of the bad MAP sensor symptoms. 


A MAP sensor that has already failed won’t give any readings and a failing one might send data to the ECU but it will be something that doesn’t make any sense like low engine vacuum while both the crankshaft position sensor and the throttle position sensor are showing the engine at idle. 


Depending on your vehicle’s make, model, and age, the MAP sensor diagnostic trouble codes or DTC will be stored in the car’s computer. The trouble codes could range from sensor faults, simple circuits, to correlation, or range faults. You can look for these codes and correct the problems that triggered the check engine light to show up. 


MAP Sensor Symptoms: Will a bad MAP sensor throw a code?


As one of the faulty MAP sensor symptoms is an illuminating check engine light, people may wonder if a bad MAP sensor can also throw some trouble codes. The ECU can fire the injector for a shorter or longer blow to supply less or more fuel depending on the voltage or readings from the MAP sensor. That is why a faulty MAP sensor won’t always set off the check engine light or lead  the car’s computer to store a diagnostic trouble code. 


However, if the car’s computer does, here are some of the list of the trouble codes that you can find stored in there that are associated with the manifold absolute pressure sensor.

  • P0068: MAP or MAF Throttle Position Correlation


The P0068 trouble code means that the ECU has received readings from the MAP or MAF which detects air flow through the induction system and the intake manifold  that contradicts the readings from the throttle position sensor.  

  • P0069: MAP – Barometric Pressure Correlation


This trouble code means that the car’s computer has detected contradictory readings from the MAP sensor and the barometric pressure sensor or the BARO. It has detected that there is too much difference between the MAP sensor voltage and the BARO sensor reading. 

  • P0105: MAP Circuit Malfunction


The P0105 trouble code means that the MAP circuit is having an electrical failure or a malfunction. 

  • P0106: MAP/BARO Pressure Circuit Range and Performance Problem


This trouble code is a general code that indicates that the MAP circuit has an issue of incorrect voltage output range or an engine performance problem. It can be triggered when the car’s computer detects that the MAP sensor’s signal voltage is irregular and does not match to the current engine load or throttle position.   

  • P0107: MAP/BARO Circuit Voltage Low Input


The P0107 trouble code means that the MAP sensor sends a voltage input to the ECU that is too low. A voltage input that is too low, .5 volt or less, means that the MAP sensor reading is lower than the normal range which could indicate that there is a problem with the MAP sensor or the wiring. 

  • P0108: MAP Circuit High Voltage Input 


This trouble code means that the MAP electrical circuit sensor has a problem and has a voltage input that is too high. The voltage input it sends to the ECU is much higher than the normal range for proper engine operation. 

  • P0109: MAP Pressure Circuit Intermittent Malfunction


This trouble code means that the MAP sensor sends intermittent voltage input signals to the ECU. It is a problem since voltage inputs that are too irregular or erratic can prevent proper engine operation. 

  • P1106: MAP Circuit Range and Performance Problem


This trouble code could mean that the car’s computer has detected an unusually high or low voltage signal detected from the MAP sensor. However, the trouble code may have a different definition depending on the car’s make and model. 


Keep in mind that other faulty sensors or parts can also set off these trouble codes. It is advised that you have your MAP sensor inspected and tested to confirm that it is the one that triggered the trouble codes or is causing bad MAP sensor symptoms. 


MAP Sensor Symptoms: How often should you replace a MAP sensor?


MAP sensors, like any other vehicle components, can also experience wear and tear over time. There are instances where they fail faster than others. MAP sensors usually fail between 125,000 and 150,000 miles depending on the age and other contributing factors. They can sometimes become damaged when the engine intake manifold is removed or during air filter changes. Accidents like collisions can also cause the MAP sensor to become faulty due to an electrical fault. 


If you are experiencing any of the bad MAP sensor symptoms and a MAP sensor replacement is required, the average cost for it is between $130 and $200. With parts that can be purchased between $110 and $180 and labor costs that can go from $15 to $46. 


MAP Sensor Symptoms: Can I drive my car with a bad MAP sensor?


Driving with a bad MAP sensor is not recommended. Driving with a failing MAP sensor can be dangerous since the power of the engine can surge on and off. It can potentially lurch your vehicle forward. It can compromise your safety since it will be difficult to control your vehicle when the  overall engine performance becomes unpredictable. 


Aside from compromising the safety of the drivers, driving a vehicle with a faulty MAP sensor can also be harmful to the vehicle itself. The fuel delivery can become excessive due to incorrect readings from the MAP sensor that can cause harm to the engine and the catalytic converters. It might become something that can be too expensive to repair if you ignore the faulty MAP sensor symptoms and continue driving.


It is best that when you notice any of the bad MAP sensor symptoms, you have it inspected and tested immediately to get the right diagnosis. MAP sensor symptoms are there to warn the drivers that there is something wrong with it and it needs immediate attention.  









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