Code H43- Knock sensor...how do I tell which one?
Thread Starter
Le Mans Master
Joined: Feb 2003
Posts: 9,087
Likes: 0
From: Chicago IL
Code H43- Knock sensor...how do I tell which one?
I can see that there are two knock sensors. I unhooked both, checked the wiring and everything looks fine. I do not have the tool to check them so how do I figure out which one?
Should I just replace both while I am at it?
Thanks!
Should I just replace both while I am at it?
Thanks!
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
KYour LT1 has two single wire OSs.
Easy Way-Replace both and hope. If that doesn't work, the problem is in the wiring or the PCM. When I got my 96 it threw an occasional O2 code. I replaced all four for peace of mind. Code never came back.
Harder way- not available to you because you don't have an FSM. It would require a pin out of the PCM so you could check the circuit for continuity. It is unlikely that both failed at once.
They are not expensive.
Easy Way-Replace both and hope. If that doesn't work, the problem is in the wiring or the PCM. When I got my 96 it threw an occasional O2 code. I replaced all four for peace of mind. Code never came back.
Harder way- not available to you because you don't have an FSM. It would require a pin out of the PCM so you could check the circuit for continuity. It is unlikely that both failed at once.
They are not expensive.
Last edited by MK 82; Sep 10, 2008 at 03:52 PM. Reason: typo
Thread Starter
Le Mans Master
Joined: Feb 2003
Posts: 9,087
Likes: 0
From: Chicago IL
Your LT1 has two single wire KSs.
Easy Way-Replace both and hope. If that doesn't work, the problem is in the wiring or the PCM. When I got my 96 it threw an occasional O2 code. I replaced all four for peace of mind. Code never came back.
Harder way- not available to you because you don't have an FSM. It would require a pin out of the PCM so you could check the circuit for continuity. It is unlikely that both failed at once.
They are not expensive.
Easy Way-Replace both and hope. If that doesn't work, the problem is in the wiring or the PCM. When I got my 96 it threw an occasional O2 code. I replaced all four for peace of mind. Code never came back.
Harder way- not available to you because you don't have an FSM. It would require a pin out of the PCM so you could check the circuit for continuity. It is unlikely that both failed at once.
They are not expensive.
Would the knock module in the PCM throw a different code?
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
I had a code 43 in my 1985 a while back. The fix turned out to be unrelated to the knock sensor itself. But I only discovered that after buying a replacement.
Replacing your knock sensors may fix the problem, but you may also be shooting the messenger. For $100, you could pick this up.
Dunno, just a thought. Agent86 has a lot of the flow charts available for these codes. Maybe if you PM him, he could supply yours.
Replacing your knock sensors may fix the problem, but you may also be shooting the messenger. For $100, you could pick this up.
Dunno, just a thought. Agent86 has a lot of the flow charts available for these codes. Maybe if you PM him, he could supply yours.
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Thread Starter
Le Mans Master
Joined: Feb 2003
Posts: 9,087
Likes: 0
From: Chicago IL
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
Safety Car
Joined: Aug 2004
Posts: 4,907
Likes: 731
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
I am having this same issue right now with my 94. I DO have the FSM and have checked the KS according to the FSM. Here is what I came up with.
Do you have a Digital Multimeter? If you do this is the process.
Remove the wire and check the the module for resistance (Ohms) between the center connection of the sensor and ground. The reading should be (IIRC) between 3200 and 4500. (One of mine was 5900, thus bad and I replaced). This did not fix my problem, either with the rough running or the Code 43. So the next step was to do a couple more checks. Which told me that it was either the problem was either the Knock sensor Module or the ECM. I now have the KS module and will replace it and I also have a reman'd ECM on it's way as well.
Do you have a Digital Multimeter? If you do this is the process.
Remove the wire and check the the module for resistance (Ohms) between the center connection of the sensor and ground. The reading should be (IIRC) between 3200 and 4500. (One of mine was 5900, thus bad and I replaced). This did not fix my problem, either with the rough running or the Code 43. So the next step was to do a couple more checks. Which told me that it was either the problem was either the Knock sensor Module or the ECM. I now have the KS module and will replace it and I also have a reman'd ECM on it's way as well.
