Parts for your 2014 Toyota Mark x-Knock sensor

2014 Toyota Mark X Knock Sensor — Purpose, Fitment and Servicing Advice

Technical sources confirm the 2014 Toyota Mark X is fitted with knock sensors. Both the 4GR‑FSE 2.5‑litre and 2GR‑FSE 3.5‑litre V6 engines in the GRX130 series use a pair of piezoelectric knock sensors mounted in the valley of the V, one per bank. Toyota’s New Car Features (NCF) and Repair Manual within Toyota Service Information (TIS) describe knock control as part of the SFI system for these engines, and include diagnostic routines for DTCs P0325 and P0330 relating to Knock Sensor Circuit Malfunction. The Toyota Electronic Wiring Diagram (EWD) for GRX130 also lists Knock Sensor No.1 and No.2 feeding the ECM for ignition timing control.

On this Mark X, the knock sensor’s job is to “listen” for detonation (pinging) inside the cylinders. When the sensor detects the high-frequency vibration of knock, the engine control module trims ignition timing and, if needed, enriches the mixture to protect the engine. It helps the V6 run crisp on our local fuels, keeps emissions tidy, and prevents piston and bearing damage from pre‑ignition. Because there are two sensors on the V6, the ECM can fine‑tune each bank independently, improving drivability and fuel economy.

It’s not a regular service item, but it’s worth a check whenever the intake manifold is off, or if there’s a check‑engine light with codes like P0325/P0330, noticeable pinging under load, flat performance, or poor economy. Visual inspection goes a long way: look for brittle or oil‑soaked wiring, loose connectors, or damage from previous work under the bonnet. Since the sensors rely on clean metal contact with the block, any corrosion or debris under the mounting pad can dull their “hearing”.

Replacement is straightforward for a pro but fiddly for DIY because the intake manifold usually needs to come off. Best practice on this Mark X includes:

• Replacing the intake manifold gaskets and any disturbed PCV hoses.
• Cleaning the block’s sensor seat, no sealant or Teflon on the bolt.
• Installing the sensor in the correct orientation and torquing to factory spec (do not overtighten).
• Routing the sub‑loom exactly as per the harness clips to avoid false knock from contact or vibration.

If the vehicle’s been running on low‑octane fuel and knocking, the sensor will be working overtime, switching to quality 95/98 RON petrol and keeping up with cooling system maintenance helps reduce knock events. Genuine or high‑quality OEM‑equivalent sensors are recommended—cheap units can have the wrong frequency response and cause timing to be pulled unnecessarily, making the car feel doughy. After fitting, clearing codes and performing a proper road test with a scan tool to confirm no pending knock sensor faults is the way to go.

• Does the 2014 Mark X have one or two knock sensors?
  It has two—one for each cylinder bank on the V6. That lets the ECM adjust timing per bank for smooth performance and engine protection.
• What are the signs a knock sensor is failing on a Mark X?
  Check‑engine light with P0325/P0330, rattly pinging under load, sluggish performance, and poorer fuel economy. Wiring damage or incorrect torque after engine work can trigger false faults.
• Can a knock sensor be cleaned, or should it be replaced?
  The sensor itself isn’t serviceable. If it’s contaminated or damaged, replace it. Cleaning the mounting pad on the block and ensuring correct torque and orientation is critical during refit.

Technical references: Toyota Service Information (TIS) — New Car Features (NCF) for 4GR‑FSE/2GR‑FSE, Repair Manual: SFI System, Knock Control and DTC P0325/P0330 diagnostics, Toyota EWD for GRX130 Mark X.