legacycentral bbs

Can anyone tell me what a knock sensor really does? I'm pretty sure it detects a knock in the engine and makes the engine run differently so it wont hurt the engine.. Mine seems to be not working and setting off the check engine light, however I never heard a knocking, and this happened twice now. You think its just a faulty sensor or something else. What would cause a knock in the engine?

You're right about what it does. It doesn't only detect knock though, any abnormal sounds/vibrations can theoretically cause the sensor to send a signal to the ECU. It retards ignition timing. I would be willing to be it is a bad sensor. If it's the original, which is fairly likely, you should replace it ASAP. There is a TSB out about it with an upgraded sensor to replace it. The first ones were prone to cracking. As for what causes an engine to knock, there's a few different kinds of knock, so various things can cause it, though in the context, preignition and detonation are the ones the sensor is looking for.

Would you know how much it costs to get one repaired? I have a 95 legacy.

if you do it yourself $50-75 dollars depending on where you get it.