Hey All- Super confused on this on going P0332 Knock Sensor 2 Circuit Low Voltage Bank 2 and P0327 Knock Sensor Circuit Low Voltage. Back Story:

A year ago I got these codes ( Assuming the same code, i don't remember exact code to be honest, but my googles said replace the sensors and harness) Didn't have the time before my road trip, so I paid a local shop to do it with my AC Delco/ OEM sensors, but they forgot to use the Duralast harness, reinstalling with the old 2005 harness.

6 Months or so later, Ping goes the CEL, same codes. I do all the work myself this time, replacing everything with AC Delco parts ( EBay, but new in Ac delco packaging) I accidentally ordered a total of 6 "new/ac delco sensors btw, so I'm armed with extras. Worth noting I also replaced all the fuel injectors ( again AC delco from an ebay seller) as well as replaced the icky looking fuel injector plug/ clips as some of the old blue style retaining clips had broken from the previous mechanics abuse. I also replaced ll my plugs and plug wires, you guessed it, AC delco parts. I generally avoid doing too many things like this at one time for these exact reasons, but i had it town down, so with 330k on the odometer I figured the van could get a birthday present.

Within 1 day, CEL pops again, so i tear it down and replace the first 2 Knock Sensors with 2 more new ones. Worth noting, the front one must have been torqued too tight, as it would not come out. The outer body and inner body had separated and therefore the nut part just spun. After some creative reasoning, it finally came out. New sensors went in at 15 Ft/Lbs. per spec, and intake put back together.

Drove 30 miles, CEL pops back up P0332 and P0327 as well as P0300 ( Random Misfire) --- I cleared these all and kept driving to experiment and hope the p0300 was a fluke, and so far i just have P0332 and P0327 pending in the OBD2. ( no hard CEL on dash yet) Ill go in a double check that the fuel injector plugs are all seated as well for good measure.

Sorry i said this was the quick version. But basically, new new new everything and immediately throwing the codes. Any insight would be super rad.

 

Do you have a wiring diagram and any test equipment like a multimeter? It sounds like you might be getting poor voltage to your sensors, so you might have a short or a broken or rubbing wire somewhere. If you can measure the voltage you are getting at the sensors, and what it is where it's fed from, you can hopefully isolate where your problem is.

 

Thanks BurntClutch-
I was able to find the Pin out diagram to the ECM and confirmed connectivity from the pigtail to the ECM. Just a simple resistance check with DMM pinged a beep on on pins 11 and 51.

I also checked the ohms on each new Knock sensor. I read ohms from the end of the new KS harness, and they both read 100 or 101k which I've read is correct. What I am NOT seeing as I test, is a resistance spike on the sensor when tapping along the block. With the DMM plugged into the KS pig tail and on the battery ground, I have a long steel rod touching close to the sensor hole and am able to firmly tap the valley cover with a small hammer via the rod. Neither sensor show a spike in ohms. When I bench tested a "new in bag" KS, it read 100 and spike to 140 when tapping lightly with a screwdriver. Maybe I'm just not able to create enough direct force on the installed and buried KS's for them to sense the vibes. Seems suspect and i assume these KS's are good. Worse comes to worse ill yank them and bench test, or swap with my last 2 new ones.

From here, it seems like replacing the PCM is the only last simple parts swap available. Seems kinda crazy

Luckily no P0300 yet ( misfire)

 

https://charm.li/Chevy%20Truck/2005/...20Diagram%208/

Give that a shot. I assumed you had a 1500.

The sensor grounds through the bolt, right? Since it's both sensors, maybe it's the connector to the PCM is a little grungy?

 

Well, quick update. I replaced the PCM with a "reflashed" unit from Flagship one. They took my VIN and programmed the PCM to it. So far ( 120 miles) and no Knock codes. BUT, new issue. I have a P0507 ( High idle) that appeared the moment the van started up after swapping PCMs. This is causing the motor to give a small lurch when taking foot off gas, as well as 2 noticeable trans downshifts when coming to start. Basically just running yucky. I was hoping that it would just work itself out, but so far nothing, and I'm starting to wonder if its unsafe to drive ( damage to itself internally?) Does any know if there is a learning period on these ?

Thanks!

 

This may be too late, since you swapped PCM's, but I read elsewhere about a batch of bad Delphi knock sensors, and a supposed GM internal bulletin warning not to use ones made prior to 10/2023. I just replaced the two on my Silverado, as the rear was reporting bad. And now it is telling me the NEW front one is bad. These were new Delphi parts from RockAuto, but if there was a bad series of Delphi knock sensors, my luck is always that I will draw the bad one.

I'm planning on repeating your test, with the wiring harness and an ohm meter, to compare the two sensors that are on the engine, to see if I get a spike. My belief is that now the rear will read good, but the front will read bad. Meaning I gotta get another one, return the bad one to Rockauto, and pull the intake manifold again.

Some of the discussions I saw elsewhere concerning potentially bad knock sensors:

https://www.gmtruckclub.com/threads/...ll-on.1054434/
https://www.silveradosierra.com/thre...o-away.744281/

That second thread has a message mid conversation, from October 2023, stating the following:

"on 9/12/2023 gm has issued an internal bulletin stating use knock sensors built after 08/23/2023 with a blue dot only. previous sensors are not built correctly causing returning codes."

I can't vouch for the validity of that statement, but it is talking about the ACDelco sensors.

I would swap back to your other PCM and see if the new problem goes away, and then consider replacing the knock sensors again.

 

HA ~ Maybe thats why they are being sold for so cheap on Ebay. Could explain many things.

In 120 miles, the knock codes never came back- Just FYI

I went ahead and swapped back to the OG PCM- It didn't even need to do a long winded relearn procedure, it started right up ( Died out once, probs since battery was disconnected) .. AC blew cold and the Idle was normal. So its got to be the PCM. I am chatting with Flagship One and i assume they will send me a new one. I wonder how fragile these units are? They shipped it in 3 bubble wrap envelops, but no box.

 

Good luck! I'm just driving with the CEL on again, and planning to deal with the knock sensor #1 (was #2 before replacing them both) when I get time. I got about 150 miles before it lit up the CEL this last time I reset it with my computer. May do that again.