Toyota Hiace Regius 2.7 (3RZ-FE) (2001): Knock Sensor Replacement

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

• socket set and ratchet with extensions
• 12 mm or 14 mm deep socket (to match the sensor's mounting nut or bolt)
• torque wrench
• flat-head screwdriver
• flashlight
• clean rags
• carburetor cleaner or electrical contact cleaner

1. Park the vehicle on a level surface, shut off the engine, and let it cool down. Disconnect the negative battery terminal.
2. Read the trouble code with a scan tool. Before replacing anything, check the sensor connector and wiring for breaks, corrosion, and chafed insulation. A poor connection, rather than the sensor itself, is a common cause of P0325.
3. On the Hiace Regius, the engine sits under the front seats in the cabin and in the engine bay. Get access to the engine through the service hatch (the engine cover in the cabin between the seats), or tilt the seats forward, depending on your body style. Remove the cover and the rear trim panel that blocks access.
4. Locate the sensor: it is threaded into the cylinder block under the intake manifold. If you can't reach it, remove the air duct from the mass airflow sensor and the throttle body, and if necessary the intake plenum. Photograph or label the connectors and vacuum hoses beforehand so you can reinstall them in their original positions.
5. Disconnect the sensor's wiring connector: press the locking tab and pull on the connector body, not on the wire.
6. Clean the area around the sensor so dirt doesn't fall into the threaded hole. Unscrew the sensor with a suitable socket and extension.
7. Wipe the mounting surface on the block. Install the new sensor on clean, dry threads without sealant, grease, or anti-corrosion compounds, because they dampen the signal.
8. Tighten with a torque wrench. The exact specification for this engine is not confirmed in publicly available materials; for sensors of this type, torque typically falls in the range of 20-45 N·m (15-33 lb-ft). Do not overtighten: the sensor works by transmitting vibration through its body, and overtightening distorts the signal.
9. Plug in the connector until it clicks, and make sure the wire does not touch hot parts or moving components.
10. Reassemble the intake system in reverse order, and check all clamps and vacuum hoses for tightness and leaks. Reconnect the battery.
11. Clear the codes with the scan tool, start the engine, warm it up, and take a test drive under load. Make sure the Check Engine light does not come back on and the engine does not knock.

• Do not drive for long with a faulty knock sensor
• The engine control unit retards the ignition timing, which increases fuel consumption and reduces power, and with poor fuel real knock can occur, which is dangerous for the pistons
• Use fuel with the octane rating recommended for the engine
• If the code persists after replacement, check the wiring from the sensor to the control unit and the connectors rather than replacing the sensor again
• If you have no experience working under the intake manifold, it is better to go to a repair shop