P0108 serious

Manifold Absolute Pressure Sensor Circuit High Input

What does P0108 mean?

The P0108 code means the vehicle's onboard diagnostic system has detected: Manifold Absolute Pressure Sensor Circuit High Input. This is a serious severity code.

Common Symptoms

  • Check Engine Light on
  • Engine runs lean
  • Hesitation
  • Hard starting
  • Reduced power

Probable Causes (Ranked by Likelihood)

  • Faulty MAP sensor producing high voltage Very High
  • Short to voltage on signal wire High
  • Blocked or crimped vacuum hose to MAP sensor Moderate
  • Failed sensor internals Moderate

Step-by-Step Diagnostic Procedure

  1. Check MAP signal voltage at idle. Should be approximately 1-2V. Above 4V at idle indicates a high-output fault.

  2. Inspect the vacuum hose for crimping or blockage. A blocked hose reads atmospheric pressure (high voltage) regardless of actual manifold vacuum.

  3. Check signal wire for shorts to 5V reference or 12V.

  4. Replace MAP sensor and retest.

Frequently Asked Questions

Can a blocked vacuum hose cause P0108?

Yes. If the hose to the MAP sensor is kinked or plugged, the sensor always sees atmospheric pressure instead of manifold vacuum, resulting in a continuously high voltage reading.

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