1997 Chevrolet
K1500 4x4 Silverado
V8 5.7L
106,000 miles


Truck has check engine light on. Had the code read and it is a faulty knock sensor and/or
knock sensor wiring. I do notice sluggishnes as described by faulty knock sensor.

Question: Where is the knock sensor located? Will it be UNDER the intake manifold? Or exposed off the side of the engine block? What is the recommended torque when reinstalling the new knock sensor? I have read that there are two on this truck, do I replace both, or should the error code tell me which one?
I have read that I should apply silicone around edges of new sensor to prevent water seeping in. Is this true? What kind of silicone?

Thanks!

Found it!

(The Knock sensor is located underside of the engine block.
Need to crawl underneath, passenger side of engine block,
Located low on the block and more forward.)


This model is supposed to only have one, so I will take a DMM to it this weekend for the
Resistance and AC readings, tighten the wires up/replace if needed.
Otherwise the P0327 error code indicates internal engine knock or fuel pressure issue.

Quote:

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Originally Posted by redeye007

1997 Chevrolet
K1500 4x4 Silverado
V8 5.7L
106,000 miles


Truck has check engine light on. Had the code read and it is a faulty knock sensor and/or
knock sensor wiring. I do notice sluggishnes as described by faulty knock sensor.

Question: Where is the knock sensor located? Will it be UNDER the intake manifold? Or exposed off the side of the engine block? What is the recommended torque when reinstalling the new knock sensor? I have read that there are two on this truck, do I replace both, or should the error code tell me which one?
I have read that I should apply silicone around edges of new sensor to prevent water seeping in. Is this true? What kind of silicone?

Thanks!

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You've already found it! Great self-rescue!

Attachment 26438

Here's a pic for those how may still be searching for yours.

Silicon? Dielectric silicon grease is the preferred. Teflon tape would suffice to insulate the sensor electrically from the engine block. Just remember, you want that sensor to detect engine knock, so too much isolation would not be good here.

Hey Captain,

Thanks for the reply... I started to attempt this replacement and think I am totally on the
Wrong track... all of my reading does not mention one thing about ENGINE coolant pouring out when I begin to remove the Knock Sensor. Help Please!!

I lost quite a bit of fluid already but plugged it back up. Now, the I thought I had located the knock sensor on the bottom of the block, passenger side area, I am underneath the truck to access this. Your diagram suggests it is on the topside. (?) I thought this truck only had one Knock sensor... I will take your diagram and look again to see another.
What do you think I had removed when the coolant came out? Looks exactly like the replacement sensor I have...


Also, the coolant should I just add more to the reservoir to Full Cold or is there more?
Thanks for your help, in a jam, will definitely support you!

UPDATE: I have now reconnected the "Sensor" which leaked all of the coolant, connected the wire, and the battery cable again. From what I hear, disconnecting the battery cable clears the service light. But, in general, how quickly will the light come back on if the problem persists? Just curious. Ready to tackle again once I know more... thanks!

After the ECM runs it's diag and if the fault isn't current, the light will go out but the code will remain stored as a history code in the computer's memory, for a while.
A closer look at the pic should show that the sensor is below the exhaust manifold and slightly forward of the starter motor. To help get the coolant to the proper level, start with a cold engine, top up the radiator first then fill the reservoir to the full cold level and drive the vehicle. Don't just let it idle or rev it because that won't "burp" the system. Recheck the coolant reservoir after your drive and periodically thereafter. If your radiator cap isn't working properly, the coolant will remain too low in the radiator
Remember, only check the radiator level with an overnight cold engine.

So, I am assuming that I am on the right track. GM combined the Knock sensor and engine coolant drain? So I should just be prepared to catch the coolant, let it drain, and replace the knock sensor and restore the coolant as you describe above?

You are very much on the right track.
You should drain the coolant first and then replace the sensor. Also, an update: use a water based caulk to seal the sensor, but still, not too much.
But, no, the two sensors have not been combined into one. The actual coolant sensor is mounted elsewhere.

***editted for clarity**** To make certain you have the proper sensor, the Knock Sensor has a single Dark Blue wire running to it.

CaptainRich,

Thanks for the reassurance, your help has been great. I have reinstalled the original knock sensor, making sure it was tightened with a good connection. After I leaked the coolant from removing and reinstalling the (original) knock sensor, I took it to the shop for a coolant flush. The coolant that I saw seemed dirty and I do not know when it was done last, if ever. Maybe unnecessary, but better safe than sorry.

The SES light is no longer on, however I imagine it is just a matter of time. Truck still seems to chugg a bit and not as powerful as I would expect on acceleration.
My next task is to replace all spark plugs and wires as I am hearing this could
Cause what I am experiencing as well. The wires look original and with 100K+ miles, this is overdue. Then when the SES light comes on again, with a knock sensor error, I will install the NEW one and know exactly what to do. Thanks for your help!

BTW: On Chevy, is the SES light and Engine symbol the same? I don't see the Engine symbol near the gauges at all and not sure there is one on this Chevy. Again, reading has confused me... some sources say the SES lights for routine maintenance at prescribed intervals or for low fluids, while the "engine" symbol throws your ECM code and indicates a system problem.

A good old fashion tune up may well help: i.e. plugs, wires, cap and rotor. Don't forget the inline fuel filter.
One key point: if it only chuggs during initial take-off from a stop, you may have a worn spot on the Throttle Position Sensor (TPS). Monitor when the chugg occurs, like engie temperature, etc. and let us know.
You may also want to consider the benefits of having the injectors professionally cleaned.

And, yes. The lights are universal and interchangable: The Service Engine Soon (SES), the Malfunction Indicator Lamp (MIL) and the Check Engine light are all the same thing. It varies depending on year,make and model.
Some instrument clusters show a small engine symbol, some show "SES", other may differ, depending on the model year or manufacturer.
The light should come on steady when the key is first turned on, then it should flash during initial start-up, then go off once the engine is running.