Yea i gotta 99 5.3 4wd, and the other day i went thru some mud. Afterwards, the serive engine soon light came on and stayed on. Well yesterday i went to balance my tires and asked them to dyno the computer to see what was up. He said that the "knock sensors on bank 2 had low voltage" He cleared the codes and it went off. Wll this morining when i started up my truck, it came on again. Does anyone know how to fix this problem. What the hell is a knock sensor and where can i get some to replace them.

 

It is probably resistance due to water/mud getting in a connection. Drive it for a while and see if the light comes on again.
Happened to me when I went mudding in my S10, it got cleared after about 3 days of driving.

 

nah ive been driving for a week now

 

Was it o2 sensor maybe? You don't have a bank 1 oe 2 knock sensor.

That sounds like an o2 sensor error, which usually means that the o2 sensors are bad if you ar running stock exhaust. You might also have an exhaust leak in front of the cats.

 

did they give you an exact code for it?

 

happened to me after muddin' too

 

If I remember it's p0332.Last month I had to replace the rear knock sensor.If you pull your intake cover off,there is a 2 wire connector that is clipped onto the back upper drivers side of the intake with a light and dark blue wire.You need to take a multi meter and check the resistance between ground and each one of these wires,you should get 90K to 110K ohms resistance,you will probley get much less.GM had a tsb on water getting into the back sensor.

 

Hey man. Can you tell me how to change the knock sensor? How much do they cost. Is hard to replace these? The code said that it was low voltage to bank 2 knock sensor. So how do i increase voltage. Please help!

 

First I would test the 2 wires with a multi meter,and look for the correct resistance.You need to pull the intake to get to the sensors(so test them first,it could be the wiring or pcm).First pressure wash the engine good,paying close attn to where the intake meets the heads(do not ask me why I know this,I will just say it took 3 hours to clean out all the dirt from the intake ports)You will need to disconnect all the elec connectors,the coolant for the throttle body,the 2 fuel lines(special tool needed),all cables,egr valve(1 bolt at intake and bend out of way)and there is a plastic tube that runs up the drivers side fuel rail to a valve on top of the intake in the front,squeeze the gray retainer,squeeze not pull(again don't ask).I think that it.
When you get it off it should be the back knock sensor(remember the multi meter)Replace it and torque to (I will find later),rtv the rubber plug ontop.Clean the intake and head gasket surface with a rag and carb cleaner(stuff small rags down intake ports)reinstall intake and electrical.
You will need inch-lb and ft-lb torque wrench,1/4inch drive metric sockets and med thread lock.I paid $34 for the intake gaskets,$54 for the sensor,and $17 for a Haynes manual(worth it).Note canadian $.
You can not increase the voltage,the sensor is what creates the voltage for the pcm,so if the sensor goes bad you need to replace it.First thing you should do is go to the dealer,talk to the service mngr and get them to scan the comp for the code,and get a print out on that code(should be about 5 pages on how to check out the sensor,well worth it,took 10 min and it was free. I will try to get the torque specs when I find my manual.

 

if it is indeed P0332, it is "knock sensor 2 circuit low frequency". i'd check the connections as everyone said above first. the odds of it failing are slim. knock sensors are piezo crystals that generate a frequency, not voltage, that is analyzed by an independent circuit in the ECM, which decides if it is actually knock or not. if you do have to change the sensor, DO NOT skimp on torque. i believe it is 8 ft/lbs.