Parts for your 2009 Nissan Serena-Knock sensor

2009 Nissan Serena Knock Sensor — fitted and doing vital work

Based on Nissan technical literature for the C25 series (2005–2010) with the MR20DE petrol engine, the 2009 Nissan Serena is fitted with a knock sensor. The Factory Service Manual (EC/Engine Control section) details the Knock Sensor (KS) and related diagnostic trouble codes P0325, P0327 and P0328, and Nissan’s CONSULT-III procedures cover testing for this circuit. MR20DE family references in other Nissan manuals (such as T31 X-TRAIL/Sentra) show the same sensor location and operation. Note: diesel M9R variants in some markets don’t typically use a conventional knock sensor, but the 2009 Serena sold widely with the MR20DE petrol does.

On the 2009 Serena MR20DE, the knock sensor listens for pinging (detonation) through the engine block and signals the ECU to gently pull ignition timing if it detects knock. That lets the engine optimise performance and fuel economy across varying fuel quality and loads, and helps protect the alloy block and pistons from damage. It’s a small piezoelectric unit bolted to the block under the intake side, and while it’s not a regular service item, it’s central to smooth running under the bonnet.

They’ll usually only look at the knock sensor when symptoms pop up. Common signs include a check engine light with codes like P0325/P0327/P0328, sluggish performance, increased fuel use, or audible pinging under load. Because the sensor lives low on the block, wiring and connectors can get brittle or oil-soaked over time, so inspection is worth doing when the vehicle’s in for major servicing.

• Maintenance tips:
  • Check the harness and connector for chafing, corrosion or oil contamination.
  • If removing the sensor, fit a new sealing washer (if specified) and tighten to the factory torque to ensure proper signal transfer.
  • Avoid over-tightening, too much clamping can dampen the sensor’s sensitivity.
  • After replacement, clear codes and perform any required idle/ECU relearn.

Replacement isn’t hard for a pro, but access can be tight with the intake hardware in the way. Many workshops can swap it without fully removing the manifold, though clearance varies. Always use a quality part that matches the MR20DE calibration. If the Serena is regularly run on lower-octane fuel or tows in hot conditions, keeping the sensor and its wiring in good nick helps the ECU keep timing where it should be, saving fuel and keeping the kilometres trouble-free.

Popular questions

Where is the knock sensor on a 2009 Nissan Serena?
It’s mounted to the engine block on the intake side of the MR20DE, roughly beneath the manifold. Access is from above or below depending on tools and lift. A torch and mirror help to spot the single-bolt sensor and its short harness.

Does the knock sensor need routine replacement?
No, it’s not a scheduled service item. It’s replaced when it fails a diagnostic test or throws codes like P0325/P0327/P0328, or if the connector/harness is damaged. Regular visual checks during major services are a good idea.

What faults or codes point to a bad knock sensor?
Common OBD-II codes are P0325 (knock sensor circuit), P0327 (low input) and P0328 (high input). Before condemning the sensor, rule out wiring issues, poor grounds, or incorrect torque. A scan tool with live data can confirm if the ECU sees a stable knock signal.