Bad/Corroded Knock Sensor?
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Joined: Sep 2005
Posts: 66
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From: Mesa AZ
Bad/Corroded Knock Sensor?
My check engine light is on, and reading DTC P0332, rear knock sensor.
In trying to diagnose it I have followed the procedures in the service manual however really would appreciate further advice.
So far:
1. I have disconnected the knock sensor connector and checked the resistance in the rear (light blue wire) knock sensor. It indicates within the spec range at 99.8 K ohms, within the 93-107 K ohm range.
2. If the knock sensor resistance is ok, the service manual then indicates to test for AC voltage when tapping on the block. If a change in voltage occurs due to the vibration then the knock sensor is said to be ok. Mine reads voltage.
3. The service manual then says to check the circuit between the knock sensor connector and the PCM for short to ground, open, or short to voltage. This test checked out ok as well.
4. Accordingly the next step is to reprogram and replace the PCM.
As I can't do that, I am wondering about the state of the knock sensor or corrosion around it.
In my infinite wisdom I had hosed down the interior of the engine bay about a month before I experienced the check engine and knock sensor error indication.
Despite the knock sensor reading AC voltage and the appropriate resistance, I am wondering if corrosion could be affecting the ground and causing the bad reading?
If it is suggested I need to replace the knock sensor, other than my local Chevy dealer, is there a better place online to buy parts?
Thanks a lot for any feedback!
In trying to diagnose it I have followed the procedures in the service manual however really would appreciate further advice.
So far:
1. I have disconnected the knock sensor connector and checked the resistance in the rear (light blue wire) knock sensor. It indicates within the spec range at 99.8 K ohms, within the 93-107 K ohm range.
2. If the knock sensor resistance is ok, the service manual then indicates to test for AC voltage when tapping on the block. If a change in voltage occurs due to the vibration then the knock sensor is said to be ok. Mine reads voltage.
3. The service manual then says to check the circuit between the knock sensor connector and the PCM for short to ground, open, or short to voltage. This test checked out ok as well.
4. Accordingly the next step is to reprogram and replace the PCM.
As I can't do that, I am wondering about the state of the knock sensor or corrosion around it.
In my infinite wisdom I had hosed down the interior of the engine bay about a month before I experienced the check engine and knock sensor error indication.
Despite the knock sensor reading AC voltage and the appropriate resistance, I am wondering if corrosion could be affecting the ground and causing the bad reading?
If it is suggested I need to replace the knock sensor, other than my local Chevy dealer, is there a better place online to buy parts?
Thanks a lot for any feedback!
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Yes, I would check the sensors for corrosion. All you need to do is remove the intake. It is very easy and a DIY project. The sensors sit in a well and the water can cause them to short out or corrode. Yhen you remove the intake, you dont need to disconnect the fuel lines. The fuel rail and injectors can be removed as an assembly and lifted off to the side and layed out of the way.
Bill C
Bill C
Drifting
Joined: Oct 2002
Posts: 1,335
Likes: 76
From: Bedford Va.
one more thing to do is add a thin bead of ATV around the edge of the rubber plugs that seal the knock sensor connection to the alum. plate.
this will keep out any water in the future.
also check the wire from the sensor. my intake manifold had a casting protrusion that was pressing and leaving a nice knife line on my wire. looked like a potential problem. I just hit it with a grinder to smooth it out.
this will keep out any water in the future.
also check the wire from the sensor. my intake manifold had a casting protrusion that was pressing and leaving a nice knife line on my wire. looked like a potential problem. I just hit it with a grinder to smooth it out.
