What is a knock sensor?
– Edith RAY: The knock sensor, as the name strongly implies, senses when there’s a knock occurring in your engine. Engine knock is also known as preignition. It’s when the gasoline in a cylinder detonates before it’s supposed to. It can happen if you have fuel with too low an octane rating, if the engine is running hot or the outside temperature is very high, or if the engine is traveling under a heavy load – like climbing a hill or accelerating hard with a couple of mothers-in-law in the back. TOM: Preignition is bad for the engine. If those extra explosions are allowed to continue over time, they can do damage. The knock sensor alerts the engine-management computer that knock is occurring, and the computer then retards the ignition timing to correct for it. RAY: So the answer is that you should fix this, especially since you love the car and presumably plan to keep it for the long haul. It’s not an emergency. It’s not something you need to rush out and do today, Edith, but it’s somet
