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P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input

The OBD2 code P0108 indicates that the manifold absolute pressure (MAP) or barometric pressure sensor is sending a high voltage signal to the engine control unit (ECU), suggesting a potential malfunction or an issue...

Definition

The OBD2 code P0108 indicates that the manifold absolute pressure (MAP) or barometric pressure sensor is sending a high voltage signal to the engine control unit (ECU), suggesting a potential malfunction or an issue with the sensor or its circuit

Common causes

  • Faulty MAP sensor
  • Vacuum leaks
  • Damaged wiring or connectors
  • Short circuit in the MAP sensor circuit
  • Faulty engine control module (ECM)
  • Barometric pressure sensor issues
  • Clogged intake manifold
  • Incorrectly installed or damaged intake components

Common misdiagnoses

  • Faulty MAP sensor
  • Vacuum leaks
  • Throttle body issues
  • Faulty wiring or connectors
  • Engine control module (ECM) problems
  • Barometric pressure sensor issues
  • Intake air temperature sensor faults
  • Fuel pressure problems
  • Exhaust leaks
  • Mass air flow (MAF) sensor issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide additional context for the problem

  2. 2. Inspect the MAP Sensor

    Visual Inspection: Check the MAP sensor for any physical damage, corrosion, or loose connections

  3. 3. Wiring and Connectors

    Inspect the wiring harness and connectors for fraying, breaks, or poor connections

  4. 4. Test the MAP Sensor

    Voltage Test: With the ignition on (engine off), use a multimeter to check the voltage at the MAP sensor connector. Compare the readings to the specifications in the vehicle’s service manual

  5. 5. Vacuum Test

    If possible, apply a vacuum to the MAP sensor and observe the voltage output. The voltage should change in accordance with the applied vacuum

  6. 6. Check for Vacuum Leaks

    Inspect the intake manifold and vacuum hoses for leaks. A vacuum leak can cause incorrect readings from the MAP sensor

  7. 7. Inspect the Barometric Pressure Sensor

    If your vehicle has a separate BARO sensor, check it for proper operation and connections. Some vehicles use the MAP sensor for both functions

  8. 8. Check the Engine Ground

    Ensure that the engine ground is secure and free of corrosion. A poor ground can lead to erratic sensor readings

  9. 9. Examine the ECM

    If all other components check out, there may be an issue with the ECM itself. Check for any software updates or recalls related to the ECM

  10. 10. Clear Codes and Test Drive

    After performing the checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  11. 11. Consult a Professional

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic for further diagnosis.Additional Considerations

  12. 12. Fuel Trim Values

    Monitor fuel trim values with a scan tool to see if they are within normal ranges

  13. 13. Check for Other Related Sensors

    Sometimes, issues with other sensors (like the throttle position sensor) can affect MAP readings. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the P0108 code