Symptoms of a Bad Manifold Absolute Pressure (MAP) Sensor: How To Test?

What is Manifold Absolute Pressure Sensor?

The manifold absolute pressure sensor (MAP sensor) works with intake air pressure to define proper air and fuel quantities required for the ignition cylinders. The MAP sensor measures the vacuum of the intake manifold, which fluctuates according to engine load, relative to the barometric pressure. [1]

By monitoring the manifold pressure, the MAP sensor provides real-time data to the engine’s Electronic Control Unit (ECU). This information, combined with inputs from other sensors such as the Mass Air Flow (MAF) sensor and the Throttle Position sensor (TPS), enables the ECU to calculate the density of the air entering the engine. This data is crucial for determining the optimal timing for injector opening and adjusting the spark advance, ultimately ensuring that the engine maintains the ideal air-fuel ratio of 14.5:1 for efficient combustion and performance. [2]

Where Is the Manifold Absolute Pressure Sensor Located?

The Manifold Absolute Pressure (MAP) sensor is commonly positioned on the intake manifold, often near or directly on the throttle body. In the case of engines equipped with forced induction, such as turbocharged engines, the MAP sensor may be situated along the intake tract before the turbocharger.

Bad Manifold Absolute Pressure (MAP) Sensor Symptoms

A malfunctioning Manifold Absolute Pressure (MAP) Sensor can manifest in various symptoms, indicating potential issues with the vehicle’s performance:

1. Check engine light illuminated: A malfunctioning MAP sensor can trigger the check engine light to illuminate on the dashboard.
   
2. Engine performance may be affected, leading to rough running or hesitation: With a faulty MAP sensor, the Engine Control Module (ECM) may not receive necessary sensor data related to the vacuum of the intake manifold to maintain the air/fuel ratio at 14.7:1. This can result in rough running or hesitation, impacting the overall performance of the engine.
   
3. Visible exhaust emissions: Visible exhaust emissions may be observed while driving due to a lean or rich air-fuel mixture resulting from the faulty MAP sensor.
   
4. Engine stalling: Intermittent engine stalling may occur due to a faulty MAP.
   
5. Lack of power: Lack of power during acceleration may occur due to the faulty MAP, which affects the engine air intake system, leading to inadequate or excessive air supply to the engine.
   
6. Poor Fuel Efficiency: Inefficient fuel consumption may be observed as a symptom of the faulty MAP, as it affects the proper regulation of the air/fuel ratio due to absence of MAP sensor data . This can result in the wastage or improper utilization of fuel.
   

Common MAP sensor fault codes

Here is a list of codes that are associated with the bad MAP sensor to look for if your check engine light has turned on

• P0068 : MAP/MAF – Throttle Position Correlation
• P0069 : Manifold Absolute Pressure – Barometric Pressure Correlation
• P0105 : MAP Circuit Malfunction
• P0106 : MAP/Barometric Pressure Circuit Range/Performance Problem
• P0107 : Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
• P0108 : MAP Pressure Circuit High Input
• P0109 : MAP / Baro Pressure Circuit Intermittent

What Causes the Malfunction of Bad Manifold Absolute Pressure (MAP) Sensor?

Causes of a Faulty Bad Manifold Absolute Pressure (MAP) Sensor

1. Electrical Wire Issues: Poor connections across electrical connectors, broken wiring, blown fuses, loss of ground, or issues with previously repaired wires can disrupt the connection with the MAP.
   
2. Clogged Sensor: Accumulation of dirt, debris, or oil residue on the MAP sensor can obstruct manifold pressure readings, leading to sensor malfunction.
   
3. Excessive Oil Mist: If excessive oil mist from the crankcase ventilation system contaminates the MAP sensor, it can interfere with its functionality.
   
4. Water Ingress: Exposure to water, particularly from driving through deep puddles or heavy rain, can cause water to enter the MAP sensor housing, leading to malfunction.
   
5. Exposure to Road Salt: Vehicles driven in areas where road salt is used for de-icing purposes are prone to corrosion, which can affect the MAP sensor’s performance over time.

How To Test Manifold Absolute Pressure (MAP) Sensor?

Testing the Manifold Absolute Pressure Sensor can be done using following method:

1. Check Voltage using multimeter:
   
   • Set the multimeter to voltage mode.
     
   • Connect the red probe of the multimeter to the signal wire of the MAP sensor connector. The signal wire is typically the middle wire, but refer to your vehicle’s wiring diagram to confirm.
     
   • Connect the black probe of the multimeter to a good ground point, such as the battery negative terminal or the engine block.
     
   • Turn on the ignition key without starting the engine.
     
   • Check the voltage reading on the multimeter. The voltage should typically read between 0.5 and 1.5 volts. If the voltage is outside of this range, it indicates a faulty MAP sensor that needs replacement.
     
2. Check Resistance using multimeter
   
   • Switch the multimeter to the ohm mode.
     
   • Connect the probes of the multimeter to the power and ground wires of the MAP sensor connector. Typically, the power wire is red and the ground wire is black, but refer to the wiring diagram to confirm.
     
   • Ensure that the ignition key is turned off to prevent any electrical interference.
     
   • Measure the resistance between the power and ground wires. The multimeter should typically read between 200 and 600 ohms.
     
   • If the resistance falls outside of this range, it indicates a faulty MAP sensor that requires replacement.
     

Other Issues That Exhibit Similar Symptoms as a Bad Manifold Absolute Pressure (MAP) Sensor

When a car exhibits the symptoms mentioned above, and the Manifold Absolute Pressure (MAP) Sensor has been checked and found to be in working order but the issue persists, it’s essential to inspect the other components of the air intake system.

1. Faulty Mass Air Flow (MAF) Sensor: A malfunctioning MAF sensor can exhibit symptoms similar to those of a faulty MAP sensor. The MAF sensor is responsible for measuring the mass of incoming air and plays a crucial role in determining the air/fuel mixture ratio. When it fails, it can disrupt fuel delivery to the engine, resulting in rough idling, sluggish acceleration, and reduced fuel efficiency.
   
2. Faulty Throttle Position Sensor (TPS): A malfunctioning TPS sensor can also present symptoms resembling those of a faulty MAP sensor. The TPS sensor monitors the position of the throttle plate and sends signals to the engine control unit (ECU) to regulate fuel delivery and ignition timing. If the TPS sensor fails, it may cause irregular engine idling, hesitation during acceleration, and poor fuel economy.
   

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