Mercury XL3Z-12A699-BA Knock Sensor

A knock sensor is used on the 4.0L SOHC V6 engine to detect engine detonation, or pinging. The sensor produces a fluctuating output voltage which increases with the severity of the knock. The signal goes to the PCM, which will retard ignition timing to stop the detonation. The knock sensor is located on the right cylinder head by the intake manifold. On 2001 and later models, the knock sensor is located below the intake manifold. Knock sensor operation and any associated problems can be monitored best with an OBD-II scan tool. If your engine suffers from detonation or pinging, have it tested with the necessary equipment by a dealer service department or other properly equipped repair facility.