P0108: Manifold Absolute Pressure/Barometric Pressure Circuit High Input

Common causes

• A failed MAP sensor
• A broken ground wire, or a loose or corroded connector
• A signal wire shorted to the 5-volt reference or another voltage source
• An open signal wire, which reads high on many designs

Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.

Symptoms

• Check engine light
• Rough idle, hesitation or poor power
• Poor fuel economy, sometimes with a fuel smell or dark exhaust
• Hard starting on some vehicles

Is it safe to drive?

If the engine stalls, hesitates badly or loses power, don't keep driving it; have it towed or checked. If it runs normally with a steady light, drive gently and get it fixed soon, since the engine computer is using a backup value instead of a real load reading.

How to check it with a scanner

1. Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
2. With the key on and engine off, the MAP reading should be close to the local barometric pressure from a weather app. A sensor voltage pinned near 5 volts, or a pressure far above barometric, points to the circuit or sensor.
3. With the key off, check the connector and wiring for corrosion, loose pins or chafing.
4. With a multimeter, back-probe the connector with the key on: about 5 volts on the reference wire and close to 0 volts on the ground wire. A bad ground is a common cause of a high reading.
5. If the sensor has a vacuum hose, make sure it's attached; a loose hose more often sets P0106, but it's an easy check.
6. After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.

A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.

Questions

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