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Switches & Sensors

MAP Sensor (Manifold Absolute Pressure)

 
  • Determines the correct air/fuel ratio in vehicles which do not have an air mass sensor
  • Uses air temperature and engine speed to determine air density
  • Measures EGR valve performance in some vehicles or used in turbo applications to monitor air pressure.

Troubleshooting:

  • Symptoms:
    • Engine RPM becomes irregular due to incorrect readings
    •  Failure of turbo
  • Possible causes for failure:
    • Circuit broken between sensor and ECU
    • Damaged wire connector
    • Spark plugs may be coated in excess fuel

Testing:

  1. In order for a MAP sensor to function properly it is imperative that the sensor is sealed as a vacuum leak can affect any readings that the sensor takes. To ensure that there are no leaks check the sensor’s gasket and the hose from the intake manifold.
  1. If both appear to be in working order then it is important to check that the sensor is receiving vacuum. This can be done by checking the sensor’s port and any hosing leading to the sensor.
  1. At this point, if there appears to be sufficient vacuum use a multimeter to see whether the sensor is receiving voltage.
  1. The sensor can also be tested by connecting a hand-held vacuum pump to the port of the sensor and a multimeter to the sensor’s connector. In normal conditions the sensor should register between 1 and 2 volts at idle (this is where the sensor is experiencing high vacuum), and around 5 volts with the engine off but the ignition turned on.
  1. If similar readings are not measured during the test with the vacuum pump then the sensor is most likely to be faulty. It is important that the test is not performed at a vacuum pressure above 20 inHg as this can damage the sensor.

Common Fault Codes

  • P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
  • P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
  • P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
  • P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input
  • P0109 Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent

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