For four-cylinder models, the knock sensor is on the engine block's backside, requiring intake manifold removal. Disconnect the negative battery cable, remove the intake manifold, and disconnect the sensor's electrical connector. Remove the retaining nut and the sensor. During installation, angle the sensor's electrical terminal slightly below the horizontal. For V6 models, the knock sensors are between the cylinder heads, also requiring intake manifold removal. Disconnect the battery cable, and remove the intake manifolds and water transfer hose. Disconnect the sensors' electrical connectors and either unscrew the sensors or the retaining nuts/bolts.