tophatjimmy

iTrader: (1)

I have no empirical proof of this but I think the voltage tolerance window of what the ls pcm deems as 'normal' is smaller than other vehicles.
The knock sensors we use cross reference to a lot of other vehicles that may not care as much about voltage variances so the manufacturing tolerances across the board may be a bit looser than our cars want to see.
For example, I have a nearly new ac delco sensor that outputs appox .250mv AC at idle and approx .520 mv AC at 2000 rpm. I purchased a brand new Delphi sensor that outputs approx .220 mv AC at idle and .430 mv AC at 2000 rpm. This may be perfectly acceptable variance for another vehicle that uses the same sensors and might never be an issue. After all, the Delphi sensor does work and does sense knock but in my ls1 motor the variance was enough to throw a p0327 code.
Wider manufacuring variance, small window of acceptable variance. That may be why some people swap out sensors and fix the problem (got a good 'tight tolerance' sensor) while others swap and fix nothing (got a normal 'looser tolerance but still in spec' sensor).

Again, I have no proof that this is the case but it kind of makes sense as to why we seem to have so many ks issues.

mice13

iTrader: (9)

I replaced the front knock sensor and the code hasn't come back. I got a light and thought it came back, but now it's for the O2 sensor.
Make sure ohms are good at the harness with it disconnected, and also check at the ecu plug with the knock sensor harness connected.

silversweetZ

iTrader: (11)

Bump, I'm having the same problem. I've read on some posts low fuel pressure can cause this as well? Does anyone have any fixes?

emurancher

I replaced my knock sensors 3 times in the last 5 years. Earlier this year I finally saved up enough money to take my 1999 Trams Am to a performance shop for a rebuild. They did a full tear down and replaced the crank shaft and pistons. They also added headers, ported heads, aggressive cam, and a dyno tune. It was awesome. We got 400hp at the rear wheels and my car felt brand new. ANYWAY, they also replaced the knock sensors and wiring harness. Well, two months go by and am getting the codes, low voltage on both knock sensors. I am going to take it back to the shop when I get a chance next week, but I am really surprised that I have this same issue after pretty much everything has been replaced and the engine is basically brand new.

1slowbusa

iTrader: (8)

So, I have only had the knock sensor code come back since the last time I posted on this thread (sorry for not following up). It happened when i was sitting in traffic on a hot summer day.

Before when i was getting the sensor code over and over again, I had the G5X3 cam installed and a LS6 intake. I decided to change the cam to a Polluter V2 cam and I installed a FAST 102 intake. At that time I installed a 160 deg thermostat because my under hood temperatures were very hot. Also, while i was in there, i checked the knock sensors and found the knock sensor not tightening down, but this is because I was removing them and installing them over and over again to try and fix my problem with the code. So, i installed heli coils where the knock sensors go. Once i got everything back together and the car running, like i said before, i have only had the code come back once and that was when i was sitting in traffic on a hot summer day.

So, I think my issue with the code is temperature related. As I understand, resistance increases with temperature. So, if the wire and knock sensor were getting hot, like that hot summer day when i was sitting in traffic, it is effecting what the PCM wants to read from the sensor, causing the knock sensor code.

I don't know if this will fix everyone problem with the Knock sensor code, but, knock on wood, i have not had another code since. IMO, if you have replaced the sensors and verified the pigtail is good, it is heat related.

Hope this helps.

69GTOby

I've been having this same problem. Long story short, a P0332 came on seemingly out of no where about a year ago. I've since replaced the knock sensors, harness, and tested the sensors and circuits, like everyone else here, to no avail. My vehicle is an '01 2500HD 6.0 with just shy of 100k miles. 1slowbusa, I was wondering if you determined for sure that your problem was heat related, and if the 160* thermostat has still proven to have solved the problem. My code returns during the first drive after clearing, as soon as it gets warmed up, even if it's about 20*F outside like it has been lately. Thanks!

Suncc49

What brand knock sensors did you replace with? I used some china ones and found them to be the source of my problem lol

69GTOby

It's kind of a long story... but the trans failed on me while towing a car. It was a Jasper trans so no surprise there. I limped it to a shop in the area and they told me Jasper wouldn't warranty the trans unless the CEL was off. This P0332 just started coming on and I hadn't gotten around to fixing it yet, so I approved the work. What could I do? It was an hour away from home. The incompetent shop did the knock sensors and then the trans. Before I even left the shop the P0332 was back on. Apparently, yes they did use AC Delco sensors, but they didn't replace the $10 harness. Anyway after lots of arguing, I basically wasn't charged for the intake labor - whatever.

So, I did the harness myself recently, thinking that had to be the problem. To my dismay, the P0332 came right back on as soon as it warmed up. I tested the sensors and inspected them while I was in there. Everything should be good!

69GTOby

My knock sensor code is P0332 for "bank 2." The sensors are mounted one if front of the other, but does it somehow actually monitor bank 1 and bank 2 individually? I don't see how it could, but I ask because I was viewing my live data with it fully warmed up and noticed that the bank 2 upstream oxygen sensor is really slow and doesn't swing as much as the bank 1 sensor.

Bank 1 swings from about <100 mV to >850 mV about every second, while the bank 2 sensor hovers around 350 to 450 mV for a few seconds at a time, and swings to extremities of only maybe 250 to 650 mV. It seems to me the bank 2 sensor has probably about had it, but I was wondering if that could actually be causing the P0332...

69GTOby

Just to give an update in case anyone cares or might benefit: I took my old knock sensor harness, cut off the sensors, and used it to wire the sensors around such that the PCM would think the front sensor was the rear and the rear was the front. Sure enough, it threw a P0327 instead of the P0332 I was getting repeatedly, so I knew there was a problem with the rear sensor even though it tests out okay and is an AC Delco unit. These things are super sensitive.

I happened to have a correct knock sensor in my tool box from something, so I threaded it into the driver's side cylinder hear. Right in the middle there happened to be a tapped hole with the correct threads. Still using my old knock sensor harness, I hooked it up so it is monitoring the front knock sensor under the intake and this knock sensor screwed into the driver's side head. So far, it has not thrown any codes. This is just until I get around to putting this knock sensor in the correct location behind the other sensor under the intake manifold.

Now to tackle some lean codes that keep coming and going. The fuel trims are pretty high and P0171 and 174 come and go lately. I swear, I feel like I got a lemon here. I have ALWAYS loved these trucks, even working on them. I always found them relatively easy to diagnose and work on, but I have never had so many problems with one before. Misfire codes, lean codes, knock codes, a bad MAF, a couple transmissions... The transmissions are the fault of Jasper, and I guess the previous owner didn't take care of the truck very well, plus it is 18 years old now... I bet if the truck was better cared for before me I wouldn't have all these problems now. I just hope I can get caught up on everything. Oh and it needs an idler arm of course, lol.

William Dickson

Have you had any knock sensor codes resurface since your last post?

I have a 2003 Silverado with the 6.0. I have changed knock sensors and wire harness but still get a code for bank 1. I have tested resistance and verified voltage to the pcm but I still get the code. it will show up and clear on it's own and then show up again. It is really frustrating. I am not sure what to do at this point.

69GTOby

No! It has not come back for me. I still have the rear knock sensor in the valley unplugged and have a wire ran over to the bank one cylinder head where I screwed in another knock sensor. The code has not returned since. Eventually, I will swap out the rear knock sensor with this one I have screwed in the head. But, I'm not in any hurry since it doesn't seem to care that it's in the head and not in the valley.

Juan Guillen

Do you have a picture of this setup?
thanks!

ic