P0108: MAP Sensor Circuit High Input

P0108: MAP Sensor Circuit High Input

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P0108: High MAP Sensor Input That Could Cost You

Look - the P0108 code means your Manifold Absolute Pressure (MAP) sensor is reporting a voltage higher than the expected range. This isn't just a minor glitch; it can lead to poor fuel economy and performance issues. Understanding this code and addressing it promptly can save you from costly repairs down the line.

MAP sensors are crucial for optimal engine performance. If the sensor is sending incorrect signals, it could cause your engine control module (ECM) to miscalculate air intake, leading to a lean or rich fuel mixture. If you’re experiencing weird engine behavior, it's time to check this code before throwing parts at the problem.

Symptoms

  • Check Engine Light is illuminated
  • Rough idling or stalling
  • Poor fuel economy
  • Loss of power during acceleration
  • Engine hesitation or misfires
  • Increased emissions
  • Unusual engine noises
  • Difficulty starting the engine

Diagnostic order

  1. Inspect the MAP sensor wiring and connectors for damage or corrosion (should read less than 5 ohms resistance).
  2. Check the MAP sensor voltage with a multimeter; it should be between 0.5V to 4.5V at idle.
  3. Test the vacuum line for leaks; it should hold steady pressure.
  4. Use a scan tool to check for related codes, especially any that indicate issues in the air intake system.
  5. If all else fails, replace the MAP sensor (cost typically ranges from $50-$200 depending on make and model).

Common questions

  • What causes a high MAP sensor reading?

    It can be caused by a faulty sensor, vacuum leaks, or wiring issues.

  • Can I drive with a P0108 code?

    Technically, yes, but expect poor performance and fuel economy.

  • How do I clear the P0108 code?

    You can clear it with an OBD-II scanner after repairs, but ensure the issue is resolved first.

  • Is the MAP sensor the same as the MAF sensor?

    No, MAP measures pressure while MAF measures air flow.

  • What happens if I ignore this code?

    Ignoring it can lead to engine damage over time, and you'll likely end up replacing more parts.

  • How do I know if my MAP sensor is bad?

    If you experience symptoms like rough idling or poor fuel economy, it's worth testing.

  • Can a bad MAP sensor affect the transmission?

    Yes, it can cause shifting issues due to incorrect engine performance.

  • Will replacing the MAP sensor always fix the problem?

    Not necessarily. Ensure all related components are checked as well.

Vehicle-specific notes

  • Ford EcoBoost (1.5/2.0/2.3/3.5L): Sensitive to vacuum leaks; ensure all hoses are intact.
  • Honda K-series (2.0/2.4): A faulty MAP can cause erratic idle issues.
  • Toyota 2GR-FE V6: Look for wiring harness issues that may cause high readings.
  • GM 2.4 Ecotec: Check for intake manifold gasket leaks that can impact MAP readings.
  • Chrysler 3.6 Pentastar: MAP sensor failures can lead to stalling issues.
  • BMW N20/N54/N55: Sensitive to pressure changes; use OEM sensors for best results.
  • VW/Audi 2.0T TSI: If replacing the sensor, ensure to clear all related fault codes.
  • Subaru EJ20/FA20: A high MAP reading can cause turbo boost control issues.
  • Nissan VQ35/VK56: Vacuum leaks can lead to false readings; inspect thoroughly.
  • Ford 6.7 Powerstroke: MAP issues can result in decreased power and efficiency.

Parts and cost ranges

  • MAP Sensor: $50 - $200
  • Vacuum Hose: $10 - $30
  • Wiring Harness: $15 - $100
  • Intake Manifold Gasket: $20 - $60

What people get wrong

  • Assuming the MAP sensor is the only issue without inspecting wiring or hoses.
  • Replacing the MAP sensor without checking for vacuum leaks first.
  • Ignoring the need for a scan tool to confirm related codes.
  • Underestimating the importance of OEM parts for replacement.
  • Neglecting to clear codes after repairs are made.

Related codes

Check out these related codes: P0107 for low MAP input, P0106 for range/performance issues, and P0113 for intake air temperature sensor issues.

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-- Hank, Master Mechanic at Mobile Master Mechanic

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