Automotive Mechanic Training - Car Repair and Maintenance - How Knock Sensor Works? - Knock Sensor Operation Full Explained

How Knock Sensor Works? - Knock Sensor Operation Full Explained What is Knock? Also known as engine ping or detonation, an engine knock is a sound and reaction that occurs when there is a second unplanned ignition or explosion within a cylinder that is separate from the regular controlled ignition from a spark plug. In other words, knock is bad news for your engine. A few things must happen for this to occur. Basically, the spark plug ignition creates a flame front that travels through the remaining cylinder space. That flame front’s movement pressurizes the remaining air and fuel mixture. Increased pressure means increased temperature, and in some cases, it gets so hot that it creates a second ignition. The second ignition creates a second flame front, and when those two reactions collide, you get knock.(P0325) What Is a Knock Sensor? A knock sensor is essentially a small “listening” device in or on the engine that detects these irregular vibrations and sounds that come from the engine block. The knock sensor picks up vibration and sound coming from the engine block, turns it into an electronic signal and sends that signal to the engine control unit (ECU). The car’s computer then judges the information and determines whether or not ignition timing should be altered. Where is a Knock Sensor Located? A knock sensor is typically attached directly to the outside of the engine block, but in some cases, it is located underneath the intake manifold How Does a Knock Sensor Work? The Knock sensor is a actual microphone screwed into the engine block. It is tuned to listen to the exact frequency of an engine knock, which is a high frequency ping. A failing knock sensor will cause all sorts of problems to engine operation, such as skewed timing controls, loss of performance and power and ever the system going to linp-in mode. Learn how it works and how to test this incredible component. (note: We allow all schools and training institutions to use our software free of charge, so long as it is not sold to others. You're encouraged to download our free automotive simulation software for more information.