Knock or detonation can occur in your vehicle even if it's in perfect running condition. This makes the knock sensor in your car that much more important, as it's your ECU's early detection system that alerts the ECU to dangerous pre-ignition. If you are modifying your vehicle for performance or even if it's just a daily driver, the knock sensor plays a huge role in how your engine runs.
Can't find your Knock Sensor Below? Try searching for your year, make or model. Good examples are "1997 Honda Civic knock Sensor", or "1991 Nissan Altima Knock Sensor" as search terms.
Knock or engine knock can often times be heard from inside the cabin. Most people describe this sound as a rattling or a faint tin knocking sound. Usually this sound can be heard during hard acceleration, however it can also occur at slower speeds. Engine knock is caused by improper cylinder combustion, either the mixture is too lean or cylinder is igniting at the wrong time.
If your Mass Air Flow Sensor or Manifold Absolute Pressure sensor goes bad, this can cause your engine to run lean. So can a failed fuel pressure regulator or even clogged fuel injectors. When this lean condition is present, you may get any number of OBDII check engine lights that are informing you of this dangerous condition. For more on how to troubleshoot OBDII issues, check out DTC Doctor.
Other issues can cause knock or detonation as well, like your ignition timing being incorrect or mistimed. If you've advanced ignition too far, this also can cause serious knock issues. Your engine running too hot and lean, could also cause pre-ignition as the cylinder chamber reaches too high of a temperature.
Some vehicles aren't equipped with a true knock sensor to replace, and for these vehicles, we recommend the use of a Knock LED, we show you how to make one here for a Mitsubishi Evolution 8.
Gasoline or fuel that is compromised can also elevate the chances of your engine knocking. Low octane, inferior gasoline or gasoline that's been left out too long or sitting can all contribute to your engine's knocking problem.
When you need a replacement knock sensor, or even to figure out if your knock sensor is any good, check out the DTC Doctor at My Pro Street for more How-Tos, DIYs and articles.