Parts for your 2017 Subaru Legacy-Map sensor

2017 Subaru Legacy MAP sensor — what it does and how to look after it

The 2017 Subaru Legacy does use a MAP (Manifold Absolute Pressure) sensor. This is documented in the Subaru Factory Service Manual for MY2015–2018 Legacy/Outback (Engine Diagnostics), which includes diagnostic routines and DTCs P0105–P0108 for the MAP circuit, and wiring showing a three‑pin sensor (5 V reference, signal, earth). The Subaru electronic parts catalogue for 2017 Legacy/Outback also lists a “Sensor – Manifold Absolute Pressure” mounted on the intake manifold. On the 2.5i (FB25) it sits on the top of the plastic manifold near the throttle body, on the 3.6R (EZ36) it’s on the upper manifold.

On this model, the MAP sensor measures the absolute pressure (vacuum/boost — though the Legacy is naturally aspirated) inside the intake manifold. The engine control module uses that pressure, along with intake air temperature and engine speed, to calculate engine load. Even though the Legacy also uses a MAF sensor, the MAP is critical for transient fuelling, spark timing, EGR/EVAP control, and barometric correction at key‑on. When the MAP goes out of whack, owners can see rough idle, flat spots, sluggish take‑off, poor fuel economy, and a check engine light with codes like P0106–P0108.

There’s no scheduled replacement interval for the MAP on a 2017 Legacy, but it’s smart to include a quick check during regular servicing. Under the bonnet, inspect the MAP and its connector for oil mist, dust, or corrosion. A lightly contaminated sensor can often be revived with electronics‑safe MAF/MAP cleaner—never use brake cleaner. Let it dry fully before refitting. If cleaning doesn’t settle the idle or clear a code, replacement is straightforward and usually quicker than chasing intermittent faults.

• Remove the engine cover, unplug the 3‑pin connector, and undo the retaining fastener(s).
• Lift the sensor straight out, make sure the O‑ring comes with it. Replace the O‑ring if it’s flattened or nicked.
• Install the new sensor squarely, seat the O‑ring, and nip the fastener to factory spec—snug, not gorilla tight.
• Reconnect the plug, clear any stored codes, and take a short drive so the ECU can relearn trims.

To avoid repeat dramas, check for vacuum leaks around the manifold and PCV plumbing, and ensure the air filter is clean. If the car’s doing lots of short trips, a periodic MAP clean can help keep fuelling sharp and economy on point across Aussie and Kiwi conditions.

Popular questions

Where is the MAP sensor on a 2017 Subaru Legacy?
On the 2.5i FB25 it’s on top of the intake manifold near the throttle body, secured with a small bolt and a 3‑pin plug. On the 3.6R EZ36 it’s also on the upper manifold, easy to spot once the engine cover is off.

What fault codes point to a bad MAP sensor on this model?
Common MAP‑related DTCs are P0105 (MAP circuit), P0106 (range/performance), P0107 (low input), and P0108 (high input). Fuel trim or misfire codes can tag along if the MAP is skewing load calculations.

Can the MAP sensor be cleaned, or should it be replaced?
If it’s just lightly contaminated, a clean with electronics‑safe MAF/MAP cleaner often restores proper readings. If there’s internal failure, cracked housing, or repeat DTCs after cleaning, replacement is the go.