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DTC code page

P0108: Manifold Absolute Pressure/Barometric Pressure Circuit High Input

Quick answer: The ECU sees the MAP signal voltage higher than the normal operating range.

Drivers also search this fault as MAP sensor high input, baro sensor high voltage, MAP signal stuck high.

Severity: medium Family: powertrain Related paths: 9
Meaning

What P0108 usually means

P0108 means the MAP signal is reading abnormally high voltage. High voltage usually corresponds to low engine vacuum or very high load, so the ECU may think the engine is under heavy load even at idle. The result can be rich running, hard starting, poor throttle response, and black smoke on some vehicles if the sensor, wiring, or reference circuit is skewed high.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Check whether the MAP reading is unrealistically high with key on and engine off or remains high at idle.
  • Inspect for a disconnected vacuum hose or port issue if the sensor is not manifold-mounted.
  • Look for rich-running clues such as fuel smell, black smoke, or negative fuel trim before blaming the PCM.
Driving risk

Can you keep driving?

P0108 can make the engine run rich and sluggish enough to foul plugs or wash fuel into the exhaust. Limit driving if the car is smoking, stumbling, or hard to start.

Moderate urgency: This code often allows short-term driving, but the right fix usually comes faster when you diagnose it early instead of waiting for more codes.
Likely causes

Common causes behind this code

  • MAP signal wire shorted to voltage
  • Poor ground causing the signal to float high
  • Sensor internally failed high
  • Disconnected or leaking vacuum hose on remote-mounted sensor designs
  • Severe engine vacuum problem that must be separated from a sensor fault

Cause phrases often tied to this code: short to voltage, biased MAP sensor, signal wire short, poor ground, vacuum hose disconnected.

Diagnostic order

Suggested workflow

  1. Confirm the MAP reading is stuck too high on live data relative to actual engine condition.
  2. Inspect the sensor ground and signal circuits for shorts to voltage or poor terminal contact.
  3. Verify any vacuum hose or port to the sensor is connected and not leaking.
  4. Compare MAP data with throttle position and fuel-trim response to decide whether the problem is electrical or truly mechanical.
  5. Replace the sensor only after wiring integrity and pressure supply are confirmed.
Avoid guesswork

Common mistakes

  • Replacing fuel-system parts because the engine runs rich without checking the MAP input first.
  • Missing a lost sensor ground that effectively pushes signal voltage high.
  • Ignoring the difference between a real low-vacuum engine problem and a false high-load sensor reading.
Repair path

Practical fix guidance

  • Correct the electrical fault or vacuum-feed issue before replacing the sensor.
  • If the sensor is confirmed failed high, install a quality replacement and verify idle MAP and fuel trims normalize.
  • Retest cold start and tip-in because those are the moments where a stuck-high MAP often causes the worst drivability.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0108

Useful when the driver knows the wording but not the exact DTC yet.

  • MAP sensor high input
  • baro sensor high voltage
  • MAP signal stuck high
Related search intent

Queries this page can answer naturally

  • P0108 code meaning
  • what does P0108 mean
  • MAP sensor high voltage symptoms
FAQ

Quick questions about P0108

Can P0108 make a car run rich?

Yes. If the ECU thinks engine load is much higher than reality, it may command excess fuel.

Is a disconnected MAP hose enough to trigger P0108?

On designs that use a vacuum hose to the sensor, absolutely. The sensor can read near-atmospheric pressure all the time and look stuck high.