Hitachi® KNS0003 - Ignition Knock Sensor

Many modern vehicles are equipped with an ignition knock sensor that detects engine pinging. Basically, it is a device attached to the engine block or cylinder head containing a piezoelectric crystal, which is sensitive to vibration in the engine caused by engine knock that accompanies detonation. Detonation, also known as ignition knock, occurs when the air/fuel mixture isn’t just ignited by the spark plug, but also by hot spots in the combustion chamber. This creates multiple flame fronts within the combustion chamber, and when they collide, the cylinder pressure increases dramatically and you'll hear a metallic knocking or pinging noise. It can be caused by using the fuel with a low octane rating, engine overheating, hot carbon deposits on the piston or cylinder head, etc.

A heavy or continuous detonation can cause a destructive impact on your engine. Using the signals from the ignition knock sensor, the vehicle computer instantly retards timing when spark knock occurs until the detonation stops. A faulty sensor can't transmit data to the computer, which leads to uncontrolled detonation that can seriously damage the engine. Hitachi carries premium ignition knock sensors that accurately detect abnormal noise and vibration frequencies in the engine, protecting it from destructive detonation. Hitachi uses the latest electronic-sensing and control technologies to make their sensors superior to the competition. Improvements in sensor accuracy lead directly to better control system performance.