Manifold Absolute Pressure Sensor Circuit High Input
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.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $30-$100 for MAP sensor
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Common Symptoms
- Check Engine Light on
- Engine runs rich (high MAP reads as heavy load, so the ECM adds fuel)
- 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
-
Check MAP signal voltage at idle. Should be approximately 1-2V. Above 4V at idle indicates a high-output fault.
-
Inspect the vacuum hose for crimping or blockage. A blocked hose reads atmospheric pressure (high voltage) regardless of actual manifold vacuum.
-
Check signal wire for shorts to 5V reference or 12V.
-
Replace MAP sensor and retest.
Common Fixes by Vehicle
What techs usually find when diagnosing P0108 on specific vehicles — tap your vehicle for the fix and the exact part:
2005-2014 GM 4.8L/5.3L/6.0L (Silverado, Tahoe, Suburban) Easy DIY
MAP sensor voltage too high, typically from loss of vacuum signal at the sensor (plugged vacuum port or collapsed hose) or sensor gone open-circuit. Replace sensor and clear the vacuum port with compressed air.
Labor: 15-30 min2005-2015 Ford Explorer/F-150 4.0L/4.6L/5.0L Easy DIY
MAP high voltage often from a disconnected signal wire at the TMAP connector. Repin or replace the connector, and replace the sensor if no damage found. Verify the PCM ground (G100/G101) integrity.
Labor: 30 min2011-2018 Chrysler/Dodge 3.6L Pentastar Easy DIY
MAP sensor reads above 4.5V constantly — usually a shorted signal wire or completely failed sensor. Replace sensor first; if code returns, wiggle-test the harness and look for chafe at the EGR pipe.
Labor: 30-45 minFrequently 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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0108 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
See All Codes & Fixes for Your Vehicle
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