Parts for your 2020 Subaru Xv-Knock sensor

2020 Subaru XV knock sensor — what it does and when to service it

The 2020 Subaru XV (Crosstrek) with the FB-series 2.0‑litre boxer petrol engine is fitted with a knock sensor from factory. This is confirmed in the Subaru Factory Service Manual for the 2020 XV/Crosstrek (Engine Control System and Diagnostics sections covering DTC P0327/P0328 Knock Sensor Circuit) and by Subaru’s genuine parts catalogue listing a dedicated knock sensor for the FB20 engine. These technical sources make it clear the knock sensor is both relevant and serviceable on this model.

On this XV, the knock sensor listens for the high‑frequency vibrations that signal detonation (engine knock). When it hears knock, the ECU trims ignition timing and, if needed, enriches the mixture to protect pistons, rings and bearings. That smart adjustment is why the car can run happily on everyday fuels across Aussie and Kiwi conditions without sacrificing reliability.

There’s no scheduled replacement interval for the knock sensor, it’s a fit‑and‑forget part until a fault crops up. However, it’s worth a look during major services: check the harness for chafing, make sure the connector is clean and snug, and confirm the mounting bolt hasn’t been disturbed. On the FB20, the sensor sits on top of the engine block under the intake manifold area, so access usually happens when other work is being done under the bonnet.

Typical signs it’s time to test or replace the sensor include a Check Engine light with codes like P0327 or P0328, pinging under load, lazy performance, or sudden drops in fuel economy. If replacement is needed, stick with an OEM‑quality sensor and follow the workshop manual to the letter: disconnect the battery, remove any obstructing intake plumbing, unbolt the old sensor, and refit the new one with the correct torque and specified mounting orientation. Over‑ or under‑tightening, or getting the orientation wrong, can make the ECU “hear” the engine incorrectly and throw off timing.

Good fuel, clean engine grounds, and sound wiring go a long way to keeping the knock control system happy. When in doubt, a scan with live data and a quick resistance/voltage check against the service manual specs will confirm whether the sensor or its circuit is the culprit.

• Common related DTCs: P0325–P0328 (knock sensor/circuit range, performance, low, high).
• Best practice: use OEM parts, correct torque, and the specified orientation noted in the Subaru service manual.

FAQs

Where is the knock sensor on a 2020 Subaru XV?
It’s mounted on the top of the FB20 engine block beneath the intake manifold area, roughly central between the cylinder banks. Access often requires removing intake ducting or the manifold for clear working room.

Does the knock sensor need regular maintenance?
There’s no routine replacement interval. During bigger services, a quick visual of the connector and harness is enough. Replace the sensor only if you’ve got a related fault code, clear knock symptoms, or test results outside the Subaru service manual specs.

What fault codes point to a bad knock sensor?
Look for P0327 (circuit low) or P0328 (circuit high), and sometimes P0325/P0326 depending on the condition. If these appear, confirm wiring integrity and mounting torque/orientation before condemning the sensor.