Parts for your 2009 Subaru Impreza-Map sensor

2009 Subaru Impreza MAP Sensor — What it does, where it lives, and how to look after it

Yes, the 2009 Subaru Impreza does use a MAP (Manifold Absolute Pressure) sensor. Technical references include the Subaru Factory Service Manual for the 2009 Impreza (GE/GH/GR, Fuel Injection/Engine Control sections), which details MAP sensor operation and diagnostics (DTCs P0105–P0108), and Subaru’s OEM parts catalog that lists a MAP/boost sensor fitted to both naturally aspirated EJ253 (2.5i) and turbocharged EJ255/EJ257 (WRX/STI) engines. Subaru also refers to it as a “pressure” or “boost” sensor depending on variant.

On this model, the MAP sensor reads the absolute pressure inside the intake manifold. The ECU uses that signal with intake air temperature and engine speed to work out engine load, trim fuel and ignition, and manage emissions. On WRX/STI models it also doubles as the boost reference, keeping a close eye on manifold pressure under load. On 2.5i models that also have a MAF sensor, the MAP unit still matters for transient load accuracy, barometric correction, and system diagnostics.

Common signs the MAP sensor needs attention include a glowing check engine light, rough idle, flat spots on take-off, higher fuel use, hard starting, or limp behaviour under boost. Fault codes you might see: P0105, P0106, P0107, P0108.

While the MAP sensor isn’t a scheduled replacement item, it’s smart to include it in regular servicing:

• Inspect the electrical connector and harness under the bonnet for corrosion or loose fit.
• Ensure the sensor’s port isn’t blocked with oil mist or carbon, a light clean with electronics-safe cleaner can restore a lazy signal.
• If your variant uses a short vacuum stub or seal, check it for splits or leaks.

Replacement is straightforward for a competent home mechanic:

1. Disconnect the battery, remove any engine cover, and unplug the connector.
2. Undo the fixing screws/bolts and lift the sensor off the manifold.
3. Fit a quality genuine or OE-equivalent sensor with a fresh seal, nip the fasteners to factory spec, reconnect and clear codes.
4. Road test and verify live data shows normal manifold pressure at idle and during a gentle drive.

Good practice is to check the MAP sensor any time the intake tract is off, after a throttle body clean, or every 50,000 kilometres. Keeping it clean and well-connected helps the Impreza run sweet, saves fuel, and avoids avoidable fault codes.

Popular questions

Where is the MAP sensor on a 2009 Subaru Impreza?
It’s mounted on the intake manifold, near the throttle body. On WRX/STI it’s often on top of the manifold where it can directly read boost. On 2.5i models it’s in a similar spot and reads manifold vacuum/pressure for load and diagnostics.

Can the MAP sensor be cleaned or should it be replaced?
Light contamination can usually be cleaned with electronics-safe contact cleaner applied to the port and tip—don’t poke it with tools. If the sensor shows erratic readings, fails basic voltage checks, or throws repeat DTCs after cleaning, replacement is the go.

What codes point to a MAP issue on this model?
Typical MAP-related DTCs are P0105 (circuit range/performance), P0106 (range/performance), P0107 (low input) and P0108 (high input). Always check wiring, connectors, vacuum leaks and intake tract condition before condemning the sensor.