The knock sensors on V6 models are located under the intake manifold, making them difficult to access. It is recommended to replace both sensors even if only one is defective. The process involves draining the coolant, removing the cylinder heads, disconnecting the electrical connectors, and carefully noting the sensor orientation. When installing the sensors, it is crucial to position them exactly as before. For VB models, the process varies depending on the engine type. For 2UZ-FE engines, the air injection pump needs to be removed, while for 1UR-FE, 3UR-FE, and 3UR-FBE VB engines, there are four sensors. The steps involve removing the intake manifold, disconnecting the electrical connector, removing the retaining bolts, and then installing the sensors in reverse order. The engine cooling system also needs to be refilled.