please help me with this. my knock sensor will throw a code in my 2002 blazer 4.3 , the weird thing is that it dont come on all the time, i drive with my scanner in the car. one day i can drive to work and almost home and no light. or sometimes right when i get down the road it will come on. i bought the new sensor, but it looks like a nightmare to change out. and a local shop wants $130 to change this one bolt sensor. but i hate to change it if i dont need to, wouldn't it come right on if the sensor is bad? if so what can be tripping it to go on?

 

It's not that bad to replace it really.......pull distributor and remove fuel lines! doesn't take all that longas for the other do a search for the knock sensor code... and follow the diagnostic chart

 

My blazer is putting out a code for bank 1 knock sensor. I'm about to do mine and see how it goes. It is like 40 bucks and I heard the same thing about it not being to hard. We will see

 

I had the knock sensor issue, I was told by an ex GM mechanic that in later software flashes for the PCM that GM decreased the sensativity of the sensor reporting. I contacted a local GM shop and asked them and they knew nothing.
I asked if I could bring the vehicle in and get the PCM flashed with the latest released and they did this. Not for free of course, the Knock code went away.

I had replaced the sensor first, did not help.

 

well it was a job to do! what the problem ended up to be was a knock sensor.. but then i had the clutch replaced but a cheesy shop, got the two wires that go to the sensor stuck in between the bell housing and the block. i had to cut the pug and remake my own wires. but i still replaced the sensor.
just for anyone who needs to do this them self's,, you do have to remove the fuel lines from the intake to the lines in the back of the connector . that was fun getting the wrench to loosen up. of course the air tube to the intake. you really dont have to remove the distributor. im sure it would make it easier but then you have to deal with the placement back in.. all i did was remove the spark plug wires on the drives side from the cap. then you look right down from there. its right there. you do have to fight with the fuel lines from the tank in the way, but i didnt see a way to remove them. but with the intake fuel lines off i could move the main lines around to get in to get to that one bolt that hold it on the block. just to say it took about a hour, and saved me about $135 bucks of some shop to do it. i do hope this helps. im sorry i wish i took some pics to show better. thanks to my friends on the blazer forms for info that i found to help me on things i cant figure out.
mike