Parts for your 2013 Subaru Legacy-Knock sensor

2013 Subaru Legacy knock sensor — fitted, what it does, and how to look after it

Technical confirmation: The 2013 Subaru Legacy (BM/BR) is factory-fitted with a knock sensor on all petrol engines used that year (FB25 2.5i and EZ36 3.6R). This is documented in the Subaru Service Manual (Legacy/Outback 2010–2014, Engine Diagnostics EC, DTC P0327/P0328 – Knock Sensor Circuit) and the Subaru Genuine Parts Catalogue (FAST/STIS), which lists a knock sensor for the 2013 Legacy 2.5i (e.g., FB-series sensor, commonly referenced as p/n 22060AA160) and for the 3.6R (EZ-series applicable part). These technical sources confirm the sensor’s presence and role in ignition control.

For the 2013 Subaru Legacy, the knock sensor is a quiet achiever. Bolted to the engine block, it listens for the high-frequency “ping” that indicates detonation (knock). When it hears anything dodgy, it signals the engine control module to trim ignition timing and protect the motor. That means fewer dramas under load and better drivability on everyday 91–95 RON fuel across Aussie and Kiwi conditions.

Because it constantly feeds back to the ECU, the knock sensor helps the Legacy optimise spark timing for power and efficiency while keeping the pistons and bearings safe. It’s especially handy when climbing hills, towing, or on scorching summer days when engines are more prone to knock. If the sensor plays up, expect a check engine light (often with codes like P0327/P0328), rough running, pinging under load, sluggish performance, or a nudge up in fuel use.

It’s not a typical “wear” item, so there’s no strict replacement interval. Still, it deserves a look during major services: check the wiring for hardening, chafing, or oil contamination, and make sure the mounting area on the block stays clean and dry. If replacement is needed, go for a quality or genuine unit, fit it to clean, bare metal, and route the harness exactly as per the factory path to avoid false knock. Don’t over-tighten, use the workshop manual torque spec and orientation. After fitting, clear any fault codes and complete a proper road test so the ECU can relearn knock control.

A few friendly tips:

• Use the fuel grade recommended in the owner’s handbook to reduce real knock events.
• If the check engine light appears with pinging, park it until checked — better safe than sorry.
• Avoid paint, sealant, or corrosion under the sensor, it needs clean contact to “hear” properly.

Popular questions

What are the signs of a bad knock sensor on a 2013 Legacy?
Common signs include a check engine light (often P0327 or P0328), rattling/pinging under load, flat spots in acceleration, rough idle, and poorer fuel economy. Sometimes the car will feel fine at light throttle but struggle on hills or when the aircon is on.

Is it safe to drive with a knock sensor fault?
It’ll usually run, but it’s not a great idea. The ECU may default to conservative timing to protect the engine, which dents performance and economy. If real knock is occurring and the system can’t manage it, internal damage is possible. Best to get it scanned and sorted promptly.

Where is the knock sensor located?
It’s bolted to the engine block under the intake area. Access varies by engine and can be a bit tight. Always follow the service manual for access steps, correct torque, and harness routing to avoid false readings.