When replacing my starter I noticed the knock sensor needs replacing. The white plastic around the metal tube is broke. The sensor is in place but could easily slip off.
I am assuming this is easy to replace...just unscrew the old one out and screw the new one in?

If i have to drive the car and the sensor slips off what will happen?

How much do these things cost?

 

If you mean the wire slips off, then your ECM will not see any possible knocking (preignition) your engine has and will not retard the timing to get rid of it. If your car is stock and you use decent octane gas this is nearly a non issue.

The knock sensor goes into a water passage, so when you remove it coolant is going to come flowing out fast and furious. Be prepared for that. When putting a new one in make sure you torque it to spec. Under torquing will make it not as sensitive as it needs to be and over torqueing will make it too sensitive.

 

so it is ok to drive it for awhile? after all the work i have been doing on it i just want to DRIVE the thing a bit...burned out turning wrenches

 

My KS is unplugged 100% of the time.

 

Easy to replace, but get ready for a bath.

 

Scorp gave you good info. The sensor, or should I say the ecm in our cars will not will not save your engine anyway. Also, when and if you do replace it, DO NOT USE silicon sealer on the threads as this will make it ultra sensitive.

 

I would replace the knock sensor promptly. Get the Chevy service manual and as others have said, torque it in at the correct torque.

It's actually a tiny microphone that listens to the engine. When it hears engine knock it sends a signal to the ECU. (Engine Control Unit)

The ECU normally will delay (or retard) the ignition advance. This stops the engine knock, and decreases engine power.

Engine knock can be caused by using lower octane gas than is recommended by the manufacturer, or by over advanced ignition timing.

It can also be caused by a "hot spot" in the combustion chamber. During high engine load, some carbon that has accumulated in the combustion chamber can glow red.

This can cause the air-fuel mixture to ignite prematurely. This is PRE-IGNITION, and it is the equivalent of taking a very large hammer and hitting the piston before it rises to the top. (TDC, top dead center) This sends a shock through the engine, and the knock sensor "hears" the knock, and tells the ECU accordingly.

The sensors run about $45 for OEM AC/Delco. The orange coating that comes on there is all the sealant you'll need. Use a box ended wrench with a breaker bar or a socket to remove it.

Although the plastic "nipple" portion of the sensor is easily broken, the round, metal part of the sensor is actually pretty sturdy. So if you have problems coaxing it off, you can even use a pair of vice-grips to unscrew it as well.