Parts for your 2016 Subaru Outback-Knock sensor

2016 Subaru Outback knock sensor: what it does and when to sort it

Technical sources confirm the 2016 Subaru Outback is fitted with a knock sensor on both the 2.5-litre FB25 and 3.6R EZ36 engines. The Subaru Factory Service Manual (2015–2019 Outback), Subaru Technical Information System (STIS), and OEM parts catalogues list the knock sensor as an Engine Control Module (ECM) input, and the model’s OBD-II diagnostics include DTCs such as P0325 for knock sensor circuit faults. So yes, it’s absolutely relevant to this model.

On a 2016 Outback, the knock sensor is the engine’s “ears”. It listens for knock (detonation) in the block using a piezoelectric element. When it detects that sharp vibration signature, it signals the ECM to trim ignition timing and, if needed, adjust fuelling. That protects the pistons and bearings, keeps the engine smooth under load, and helps maintain decent fuel economy and power on everyday 91–98 RON petrol across Aussie and Kiwi conditions.

There’s no scheduled replacement interval for the knock sensor. It’s a fit-and-forget part until it isn’t. During routine servicing—especially when access is available under the intake—techs will usually check the harness and connector for heat or oil damage, ensure the mounting boss on the block is clean, and confirm the sensor hasn’t been knocked or misaligned. If replacement is needed, using an OE-quality sensor matters, cheap units can skew sensitivity and make the ECM pull timing unnecessarily, costing power and economy.

Fitting tips a workshop will follow: mount to a clean, dry block surface, align the sensor as per OE orientation marks, torque the bolt to specification (not “by feel” with a long spanner), and don’t apply grease between the sensor and block. Over- or under-tightening, or rotating the body on the bolt, can dull its “hearing” and lead to false knock or missed events.

Drivers will usually notice a faulty knock sensor by a check engine light and codes like P0325, lazier performance (the ECM plays it safe), rough running under load, or worse fuel use. If that light’s on, it’s best not to keep belting up hills with a caravan—get it scanned and sorted. Keeping connectors clean, using decent petrol, and fixing any intake or exhaust leaks that can trigger knock are simple ways to help the sensor and ECM do their thing for the long haul.

• Common signs of trouble: check engine light (P0325–P0332), pinging on acceleration, sluggish performance, poor economy.
• Typical location: beneath the intake manifold on the FB25, at the top-centre of the block area, accessible with the right intake removal steps.

FAQs

Where is the knock sensor on a 2016 Subaru Outback?
On the 2.5L FB25 it’s mounted on the engine block beneath the intake manifold area, centrally located to “listen” to both cylinder banks. On the 3.6R EZ36 it’s similarly positioned on the upper block. Access usually means lifting the intake gear, so most owners leave this to a workshop.

Is it ok to drive with a P0325 knock sensor code?
It’ll usually run, but the ECM may pull timing to protect the engine, which means reduced power and higher fuel use. If any pinging is heard under load, avoid heavy throttle and get it checked promptly. Prolonged driving with real knock can damage pistons and bearings.

Should they choose OEM or aftermarket for replacement?
An OE or OE-equivalent sensor is the safer bet. The ECM is tuned around a specific sensitivity and frequency range, off-spec sensors can cause false knock or missed events. Quality aftermarket from known brands can work, but workshops often prefer genuine to keep drivability spot-on.