P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input

P0108 indicates a high input from the manifold absolute pressure or barometric pressure circuit. The signal is higher than expected for the operating condition.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not diagnose a high MAP input as a boost problem until the sensor circuit and key-on pressure reading are verified.

Symptoms of P0108

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0108

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Check for short-to-voltage, open ground, poor connector contact, or a MAP signal that is stuck high.
Compare key-on engine-off pressure data with local barometric pressure and observe the signal during cranking and idle.
Inspect intake leaks, boost control issues, and sensor port problems if the vehicle is turbocharged or supercharged.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.