Hello. I've been using Corvette Forum for years now and everyone is always so helpful, I usually can find an answer to any issue I'm having. Unfortunately, I can't find a definitive answer regarding my knock sensor problem. I'll try and be as thorough as possible. I replaced the oil pressure sensor on my 2002 Z06, and I did it by removing the intake manifold instead of some of the other suggested methods. Put everything back together, drove it a few miles, and I got the two knock sensor codes, P0327 and P0332. I didn't realize it, but during reinstallation of the intake, I severed the wiring harness to the knock sensors (it was very brittle). I decided I would just replace the knock sensors at this point. Ordered AC Delco knock sensors and wiring harness. Installed new knock sensors and made sure to tighten to 15 ft-lb as the Forum stated. Installed new wiring harness, put everything else back together, and started vehicle. Check engine light came back on within a few miles of driving with the exact same codes. Now I'm stumped. Is there a "relearn" phase with new knock sensors and the PCM?
Here is all my information. I'll try and answer all of the questions I've read from other posts:

- First, I am not a mechanic. I'm just a guy that can read instructions and follow directions.

- Prior to removing the intake manifold, my vehicle had zero DTCs. In fact, I have never had a DTC for either knock sensor.

- I DO NOT have engine knock. At the most, there is a very faint lifter tick, but if I'm being honest, that's just me trying to be as descriptive as possible for you guys.

- I actually tried a second wiring harness before creating this post, with no luck.

- Battery and alternator are less than a year old. Battery is a RedTop Optima. Alternator is AC Delco. I am limited with electrical knowledge, but voltage seems to be normal.

- I replaced the intake manifold gaskets with Fel-Pro gaskets. Intake was torqued down properly following the torque sequence.

- Oil was changed at the time the pressure sensor was replaced. I always use Mobil 1 Full Synthetic along with a Mobil 1 filter.

- Vehicle is completely stock performance wise. Only real upgrade is the DeWitts radiator I installed.

- I had no water in the valley as some of the other posts mentioned. Everything looked very clean.

I hope that is enough information. I live in California and of course this is all happening with my smog being due this month. Only thing that makes any sense to me at this point is that there must be some recalibration for the new knock sensors. However, I don't know if that's accurate. Any help is very much appreciated!

 

If the connectors are the same try the old knock sensors, you had no issue just a bad harness prior. On a prior thread someone stated they had issues with dorman sensors. You bought the delco or delphi units but they make a ton of these things so the chance you got a junk one is a possibility. There is no learn procedure for knock sensors they just generate a signal.

Double check the harness also just to make sure the pins didn't get pushed in or any corrosion. You could also ohm check your new harness to check that wiring.

 

Thank you for the quick reply. I was hoping I just needed to be patient. I will have to check the harness itself. I had considered a faulty new sensor, but thought since both codes are being thrown, it must be with the wiring itself. Unfortunately, I can't try the old sensors. They were just as brittle as the wiring harness was. The plastic piece essentially crumbled when I removed the connector.

 

Hope you don't mind me butting in. I'm in pretty much your EXACT situation, and it's likely what will solve the issue for one of us will solve it for both of us.

Almost 6 months ago I opted to "upgrade" my '01 LS6's valley cover plate & PCV to the '04 LS6 version. "While I was in there" I replaced the old knock sensors and wire harness (which were fine, didn't throw any codes).
Put in AC Delco 213-3521 sensors purchased from Summit Racing, as well as the Dorman 917-033 harness.

Well, not too long after, P0327 & P0332 started popping up and still continue to persist. Talk about annoying! It's kept me from driving the car at all lately.
I started doing my own diagnostics. My most recent progress is posted here: https://www.corvetteforum.com/forums...post1606074790

But long story short, my AC Delco knock sensors seem fine by all measurable standards (ping test and resistance measurement), though I didn't save my old sensors to compare against. New harness shows near-zero ohm measurement so it should be fine too.

It may be something simple like the latest AC Delco sensors output a lower voltage than our originals, just low enough to trip a monitor. A source I came across mentioned this possibility but I can't find it now.
I'm tempted to fire the parts cannon and just get NAPA ECH DKS238 knock sensors, at least if they didn't solve the problem I could readily return them. After all, it shouldn't be a PCM harness issue since everything worked fine 6 months ago...

Unfortunately I don't think this is the case. Granted I've cleared codes several times at this point, but mine's persisted across ~1k miles in 5 months (of daily driving).

Ahhh. Where in CA? Thankfully my last smog was a year ago so I skip this year, otherwise I would absolutely be feeling your current stress But of course I'll need to resolve mine in the next 11 months.

 

Just as reference, I had 3 bad BNIB Delco IAT sensors from Rock Auto. Seems that even the quality manufacturers are having issues.

 

Specifically in the case of AC Delco knock sensors, mine test fine on the bench. But it is still an unfortunate circumstance...

 

I do not mind at all. The more information the better. Unfortunately, your reply and post are what I'm afraid of. I haven't gotten the opportunity to go in with a multimeter and test everything yet, nor do I really want to lol. Chasing down electrical issues is like trying to read a foreign language for me. Mechanical issues make sense. Electrical, not so much. In any case, I feel like everything will check out fine, just as your experience has been. I originally replaced the wiring harness with Standard Motor Products harness from Rock Auto. When the codes returned, I was convinced it was the wiring harness. Ordered a Genuine GM harness 12601822, and the issue persists. Like you, zero issues before replacing the knock sensors, and like you, I used the identical AC Delco replacement. I have read about the NAPA knock sensors and am curious to see if the Delco replacements have been the issue all along. Nevertheless, when I have time, I will go in with a multimeter.

I'm located in Tracy.

 

They all worked per say, but they all tested different. One registered -36 no matter the resistance, the other registered nothing BUT negative numbers and the third one of the terminals was loose.


I just replaced one of my knock sensors when I took the valley cover off to check pushrod length...... now I am worried.

 

Went ahead and fired the parts cannon, NAPA Echlin DKS238 knock sensors are on order. Worth a shot... You've motivated me to push ahead on this sooner than I probably would have otherwise. Hoping I can get positive results on mine soon to help with your smog test situation!

Depending on how you routed the knock sensor harness, you may be able to disconnect it from behind the intake mani without disassembling anything. This would allow you to at least check resistances of each sensor. Similarly, you could use it to do a "ping" test (measure AC voltage after knocking on the exhaust manifolds).

Surely by now you can remove the intake mani blindfolded, right? Hopefully it will be okay, but if not then we are all in this together.

 

When I damaged one of mine I replaced it with the Dorman kit. I have had zero issues while driving or data logging. Others have said they experienced problems with the Dorman stuff though.

 

I'm hoping for the same, man. I actually have a good feeling about it! I appreciate all the help. And yes, I have access to the knock sensor harness connector. I will probably get to that tomorrow. Yay

 

It is easy to pinch the harness installing the intake and forum members have reported engine codes with a pinched harness.

 

I came across this info as well. Can't speak for @American Legend but I verified the intake wasn't pinching the harness, and even taped the harness down to keep it in place during intake reinstallation.

Good luck to both of us! Will be a few days out for me, tentative delivery of sensors is Tuesday.

Good info Wish it wasn't such a "luck of the draw" situation.

 

I can not for the life of me figure out how to multiple quote on here, even though I see the "mulit quote" button. So, I will reply individually.

MetalMan2, I woke up this morning and decided I was just going to head to NAPA and get this done. Stupid smog has me antsy. The replacement sensors appear to be in stock locally. I know this issue might fall outside of common sense, but between yours and mine issue, to me at least, all signs point to faulty BRAND NEW AC DELCO, WASTE OF TIME, MONEY, ENERGY, KNOCK SENSORS. (Sorry, I needed to vent a little there). I will report my results later.

93Polo, thank you for that info. I will check to see if I accidentally pinched the harness when I remove the intake again. I usually am very careful, and probably like a lot of people on the thread, I've pulled the intake so many times, I should know better than to pinch the harness on reinstallation. But, it is a possibility.

Thank you to everyone who has pitched in!

 

Wow! This is why I love CF! I think between @MetalMan2 and @schmuckingham , you both were correct. I purchased my AC Delco knock sensors from Rock Auto and either they were both defective out the gate or they put out a lower voltage than the originals. I swapped them both out this morning with NAPA's DKS238SB and so far no stupid light. I've ran errands, hopped on the freeway, opened her up, and still no light. Previously, the light would come back on before I even hit the freeway from my house. So, fingers crossed, but I think the issue is solved!

I'll report back if the light returns, but for now, MetalMan2, I think this may be our issue. Just so you know, I used NAPA's wiring harness as well, p/n 730-6778. For all I know the other wiring harnesses worked fine, however, I just wanted it all to match. Just wanted to give all information.

Thank you to all that commented. Believe me, I took everyone's advice during reinstallation. Here is the visual difference of the two knock sensors for anyone that is interested. (NAPA on the left, AC Delco on the right)

 

This is fantastic news!! Gives me a lot of hope and I'm glad I didn't hesitate to place my NAPA online order.

Since I already bought an oscilloscope, it could be a neat idea to set up both AC Delco & NAPA knock sensors in my vice and compare their AC voltage response from a ping test. Could be telling...

 

My NAPA Echlin knock sensors came in 3 days ago and I swapped them in 2 days ago, keeping the new-ish Dorman wiring harness.
Did a quick test drive last night around the block (after completing other unrelated work), and today commuted 50 miles. So far, so good! No CEL and also no stored fault codes.

So how about that? It's a bit unnerving to think that we can't rely on AC Delco parts...

 

It is crazy, but I am glad the NAPA knock sensors worked for you as well. This was a maddening issue for me. Hopefully this thread helps others down the line.

On to my clutch issue...

 

Just out of curiosity, where are the NAPA and AC Delco sensors made?

 

AC Delco: Mexico
NAPA: USA