Parts for your 2015 Subaru Outback-Knock sensor

2015 Subaru Outback knock sensor — what it does and when to sort it

Yes, the 2015 Subaru Outback runs a knock sensor. Technical references including the Subaru Factory Service Manual for the 2015 Outback (Engine Diagnostics section listing DTCs such as P0325/P0330) and Subaru OEM parts catalogues confirm a fitted knock sensor on the 2.5i FB25 models, with the 3.6R EZ36 typically using a pair, one per bank. So it’s absolutely relevant to this model.

The knock sensor’s job is simple but crucial: it listens for knock (pinging) in the cylinders and signals the engine control module to tweak ignition timing before things get unhappy. That protects the engine from damage, helps it make the best power it can on local 91/95/98 RON fuels, and keeps economy tidy. It’s a small piezoelectric microphone bolted to the block, but it does a lot of heavy lifting behind the scenes.

There’s no scheduled replacement for the knock sensor on a 2015 Outback, but it’s smart to give it a once-over during major services. A technician will check the harness and connector for brittleness, oil intrusion, or green crusties, and make sure the mounting point on the block is clean. If replacement is needed, fitting is straightforward but fussy: the mating surface must be spotless, the sensor must be oriented correctly (the clocking matters), and the retaining bolt should be torqued to the exact spec in the Subaru manual. Over-tightening or rotating the sensor can skew readings.

Common signs the sensor or its circuit needs attention include a Check Engine Light with P0325/P0330, dull performance, rough running under load, or persistent pinging. If swapping it out, go with a quality OEM-equivalent part, disconnect the battery first, and be prepared to remove intake ducting and covers for access (on the FB25 it sits on top of the block under the intake manifold, the EZ36 has one per bank). After replacement, clear codes and let the ECU complete its relearn with a few gentle heat cycles. As always, running decent fuel and keeping up with regular servicing helps the ECU and knock control system do their best work.

• Inspect wiring and connector condition during major services.
• Replace only if fault codes/symptoms are present.
• Use correct orientation and torque from the Subaru service manual.

Popular questions

Where is the knock sensor on a 2015 Subaru Outback?
On 2.5i FB25 models, the single knock sensor mounts on the top-centre of the engine block beneath the intake manifold. On 3.6R EZ36 models, there are two sensors, one on each bank under the manifold. Access usually means removing intake ducting, engine covers and sometimes brackets for room.

Can you drive with a faulty knock sensor?
It’ll often run, but it’s not wise. The ECU may pull timing heavily to stay safe, leaving the car feeling flat and thirsty. Worse, if real knock isn’t being caught accurately, the engine can be at risk under load. Best bet is to diagnose and repair promptly if a P0325/P0330 code or symptoms pop up.

What does replacement cost and how long does it take?
In Australia or New Zealand, expect a quality sensor to be roughly the low hundreds for the part, with 0.7–1.5 hours of labour depending on engine and access. Typical drive-away pricing lands around the mid-$200s to $500 range for a 2.5i, the 3.6R can be more due to twin sensors and extra access time.