P0108 on a Subaru: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive, but the engine may idle rough, hesitate, and use more fuel until the sensor is fixed.

What P0108 means on a Subaru

On a Subaru, P0108 means the manifold absolute pressure (MAP) sensor voltage is higher than the computer expects. Subaru uses MAP sensors on a range of engines, including boxer four-cylinders, and the reading helps control fuel delivery. A bad reading can cause rough idle, hesitation, and worse fuel economy.

Is P0108 common on Subarus?

Imprezas, Legacys, Outbacks, and Foresters can see P0108 as they age, usually from a failing sensor or chafed wiring. On Subarus it is worth checking the harness where it passes near heat and moving parts, since that is a common damage spot.

Commonly reported on: Impreza, Legacy, Outback, Forester.

Symptoms

Check engine light on
Rough idle
Hesitation when accelerating
Poor fuel economy

Common causes

most common: Faulty MAP sensor
common: Signal wire shorted toward 5 volts
common: Chafed wiring near heat or moving parts
less common: Corroded or loose connector terminals

How to fix it

Fix	DIY?	Typical cost
Replace the MAP sensor	Yes	$40–100
Repair the wiring or connector	Mechanic	$60–160
Have a shop replace the sensor and verify the circuit	Mechanic	$140–260