Could just be bad knock sensors. You didn't clean your engine or drive in some really wet conditions lately have you?

 

No, I really haven't driven it in really wet conditions. I noticed the code coming on more and more lately.

 

Well, this is probably what you are looking at:

PO332 Knock sensor 2, Check engine light

 

so, it should be replaced, even though its the voltage...

 

Well, that is one possibility. I think it is a good possibility. I would say to check the two sensors before you replace them, but at that point, you might as well replace them. It could be a problem with the wiring to the sensor or according to the code, it could be an ECM problem. Just to check the wiring, I think you have to pull the intake off.

You could take it in to have a professional troubleshoot it for you, but that is going to add a big bump to whatever the eventual cost of the fix is. This is one of those things where you will have to weigh the risks vs rewards and decide what to do. I would wait for some additional opinions and do some more research online before I made up my mind one way or the other. I just personally think you are looking at replacing the sensors to be the ultimate solution.

 

Ok, well now that I know my options, I was going to replace my alternator because it said "low input voltage", so i figured, well, it must by alternator. Guess not. It isnt that big of a deal right now. I just got it inspected, it is older, with a lot of miles on it. I will probably not do anything until I either have to get it inspected, or something actually happens. But, on the other hand, what can happen if I don't replace them?

 

From what I read, it sounds like you might loose a mpg or two but not much else. Eventually however, it could start causing more symptoms besides the CEL and bad fuel mileage....

Here is the technical data on the P0332 code:

P0332 DTC Code Technical Description
Knock Sensor 2 Circuit Low Input (Bank 2)
What does that mean? A knock sensor tells the engine computer when one or more of your engine's cylinders are "knocking", that is, exploding the air/fuel mixture in a way that delivers less power and can be damaging to the engine if prolonged. The computer uses this information to tune the engine so that it doesn't knock. If your knock sensor on Bank #2 is generating a low output voltage (perhaps under 0.5V), then it will trigger a P0332 DTC. This P0332 code may show up intermittently or the Service Engine light may be lit constantly. Other knock sensor related DTC codes include P0325, P0326, P0327, P0328, P0329, P0330, P0331, P0333, and P0334.
Symptoms
You may notice drivability problems including fluctation engine RPM, a loss of power, and perhaps some hesitation. There may also be other symptoms.
Causes
Potential causes for a P0332 DTC include (but are not limited to): The knock sensor is faulty and needs to be replaced There is a wiring open/short/fault in the knock sensor circuit The PCM/ECM has failed
Possible Solutions
Verify the resistance of the knock sensor (compare it to factory specs) Inspect for broken/frayed wires leading to the sensor Check the wiring and connections leading to/from the knock sensor and PCM/ECM Verify proper voltage is reaching the knock sensor (e.g. 5 volts) Verify proper grounding of sensor and circuit Replace the knock sensor Replace the PCM/ECM

Read more at: http://www.obd-codes.com/p0332
Copyright OBD-Codes.com

 

So, it won't really damage the engine if I let it sit for too long. But, how long is "prolonged"? a week, a month, a year or two?

 

Nicholas: I have no idea to tell you the truth. I would fix it asap, but I understand that you might not have the time or money right now. From what I read, as long as there are no performance issues, it doesn't seem to be a big deal in the short term. But that is just an opinion. I personally would not let it go on very long. As soon as you can get the time and parts, do it. Keep us posted.

 

Well, time and money isn't the issue, its just, when do I want to be able dedicate at most half a day to work on it with the patience. Yeah, time might be a bit of an issue, with me starting school in September, but I still would be getting home at 3, and only really having till 9 to work on it. (I have to get up at 5 to catch my bus at 6), so 9 is really my deadline for time at night, but, thanks for the help, and I will do this as soon as I can.

 

Bad knock sensors are not able to detect detonation, resulting in horrible timing as a safety measure. This kills power and can lead to engine damage. My truck sounded like a diesel with a bad knock sensor.

The job takes around 3 hours the first time, if you have all the tools. Get AC Delco parts, $30 on Amazon per sensor, replace them both. Also get the replacement harness, you do not want to have to pull the intake twice! Put high temp RTV on the boot lip of the harness, and use it to build a half moon dam to prevent water from entering the sensor hole.

My front sensor hole was filled with water... cant imagine that being good for it.

 

Will do, Thanks!

 

Above os correct, replace in pairs and get the two sub harnesses for sure.

 

in this case, low input voltage means "no input voltage" as power isnt making it to the knock sensor because it is likely water fouled (ruined)

if you're still not convinced a quick way to verify this is check for 12v at the pigtail (i think) coming out from under the back driver side intake manifold area, it practically clips about an inch or two away from the intake manifold, on the harness side connector you should see voltage, if you do, the knock sensor is bad, since its the sensor not taking the voltage and doing its trick.

--comments from my repair below--

if you are anything like me, you will want to dedicate about 3-4 hours if you have a hand, if you're doing it yourself maybe 5 hours (first time) that way you can clean the intake valley VERY good, scrub, scrub, scrub,

(think they're going to clean anywhere near this good if you take it in for this repair?)

IF you dont have a dremel, now would be the perfect time to get one you will need it, or some type of round wire brush to manually scrape the knock sensor holes...they will be at the very least crusty and dirt and worst case rusted and corroded...these really need to be as clean as you can possibly get them, had i had a power tool i would've cleaned it much better

(i was dis-satisfied with the look of mine after the repair was over but i was still thorough and the code hasnt came back...this is just my one regret) also if money isnt an issue a second tip might be to possibly replace the entire lower intake valley and gasket you'll have a nice clean plate to secure your knock sensors to, the plate is only about $50 dollars online. but a dremel and an extra 30 minutes of polishing will get the entire thing looking OEM.

Also be sure to perform the TSB using RTV Silicon (i used grey or black to match the sensor boots) and create a 3/4 moon shape around the rear (KS2) knock sensor...remove the rear foam (or both your choice, but def. the rear) so that future water/debris can be pushed out the back of the engine,

The issue here is that the engines are slightly inclined, slanted backward if i remember correctly, and the foam blocks under the intake manifold trap water in the valley and it wreaks havoc on the system.

http://www.corvetteactioncenter.com/tec ... t-396.html

 

That is an excellent write up. I added the half moon of RTV to the front sensor too, it was the one full of water on mine.

 

This problem seems to be isolated with the NNBS (1999-2006) trucks. Is that assumption correct? Or is it just going to take a few more years for the problem to surface in the newer trucks?

 

good question, and i cannot speak for the new'er trucks, but if im not mistaken on the LT1 engines the knock sensors seem to have been relocated to the outer crank case similar to the way they're moutned on SBC's

 

Well, I have come to a conclusion to not do anything about the sensors because the engine has 250K miles on it. Just, getting into the intake on it isn't worth it unless I'm going to go all the way to the bottom of the engine. I did get a new alternator because that's what my dad seems to thing is wrong with it. He says that they are really sensitive when it comes to voltages. My old alternator was only putting out 13.7 volts, and my new should be putting out 14.4 volts, I haven't checked it yet. And yes, my dad said that it would be more worth it to throw a new engine in it if it blows up in 1,000 miles rather than attempt to just replace the sensors.

 

To each their own... with some tlc, that motor could run for another 150,000 miles. Doesnt make sense to not buy $125 in parts and spend 3-4 hours fixing it.

 

I don't know... My dad said that he doesn't want to get into it because he feels like hes going to just end up redoing the entire thing... which, me only being 16, could wreck the truck, along with everything that we do to it.

 

you need to show your dad that TSB, you're throwing away good money and parts at the wrong issue...trust me... the cost of that alternator could've covered the entire parts list for the knock sensor repair all you and your old man gotta do is get your hands dirty and fix tear the intake off...its not hard really...it looks like alot of work but its rather simple if you take your time....here's a good video:

and if you leave the knock sensors un-repaired you're going to be allowing pre-ignition detonation to occur in the cylinders which will literally cause over-heating and your pistons to become scored or possibly blown...

here's what a failed or ignored knock sensor looks like when it decides to have its way with your piston/cylinder:

 

Well, I have driven the truck quite a bit since replacing the alternator, and the light hasn't come back on, since it only would come on if the truck was running at about 2000 RPM for a certain amount of time. So, I'll see where that gets me.

 

Update: I found some time to replace the knock sensors, and all went well. I got the intake off the engine, and cleaned it off, and the engine is in fabulous condition for having 250K miles on it. It was pretty dirty, but 2 cans of brakeclean and half a box of shop towels later, it shined like it was new. The mounting plate for the sensors, was in perfect condition with no rust, and the new ones fit like a glove. The truck is all back together now, running like a champ.

 

Very good, so no more CEL's and it is running correctly. Nice to see a 250k truck still on the road.
At that mileage, a lot of people might have just given up and traded it in for a few bucks or just driven it until it died. Maybe another 250K???

 

hopefully another 250K! but... the CEL did come back on. Right before we did the sensors, I got a code come through for an o2 sensor, and now it says that I have an issue with my mass airflow sensor. Both fairly easy fixes, but I think that my airflow duct isn't set right because it has a messed up hose clamp and won't loosen, so I had to try to put the duct on the throttle body with a tight clamp, and it might not be correctly seated and leaking.