I have changed both my knock sensors all my spark plugs and wires the check engine light goes off and I drove it over 115 miles to reset the not ready codes to get my car inspected once I get it down to one not ready where it’s eligible to get inspected my check engine light comes back on and it reads knock sensor bank 1 or bank 2 not both but one or the other I have changed them both multiple times they are good. What could make it be reading those codes still even though they’re changed and good?
After you change them the computer requires a certain amount of driving before it will turn the monitor to “ready”. I’d guess either the new sensors are faulty, the install wasn’t done correctly, or the associated wiring. Sorry, I haven’t much experience w/knock sensor problems. Are you sure there isn’t an actual knock occurring, and that the sensors are in fact working and detecting the knock? Try a different gasoline, maybe a high octane, see if that helps. Other knock-causing things are an incorrect spark plug gap, incorrect ignition timing, faulty valves or valve timing, incorrect air/fuel mixture, cooling system overheating. Any indications for those? Knocking more likely on rapid accels, going uphill, so maybe you can squeak by for inspection purposes by not doing any of that temporarily, just enough to get the monitors to “ready”.
For best help here, suggest to post the car’s make/model/year/engine/trans configuration.
2004 Chevy Tahoe V8 automatic
There is no knock we changed them both out multiple times to be sure they weren’t faulty and we drove it the amount of miles and time necessary to reset the monitor. The check engine light stayed off until we got all the way to one not ready code which is required to pass inspection at first when the check engine light came back on it was reading bank 1 sensor now it’s reading bank 2 sensor I know the sensors are good and properly installed. We also changed the spark plugs and wires and I’m pretty sure they are gapped correctly. Is there a way to just reset the computer or monitor temporarily just so we can get it inspected?
Not as far as I know. Those monitors are for emissions purposes, and can’t be bypassed if part of the inspection is to verify the car’s emissions are within fed limits. A friend of mine in LA had the readiness monitor problem, told to “just drive some more”. Didn’t work just normal driving, so she drove all the way from LA area to Las Vegas and back. Still didn’t work. She had to take her car to the dealership, pay them $350 to get the monitors to ready. I expect that is what you may need to do.
Yes I’m afraid you’re probably right. Thank you so much for your help and feedback
couple of things:
-Chevy has a pretty specific drive cycle before it will complete all the readiness sensors. Google “Chevy 2004 Tahoe drive cycle” for details.
-the knock sensors are finicky on these things. I have heard lots of issues with cheap parts. Lots of folks recommend using only a/c delco knocks sensors and to replace the wire harnesses at the same time. If you used Amazon or Dorman or something else, this could be the issue. How exactly do you “know the sensors are good”?
-you can get someone to clear the codes, but you will need to complete the aforementioned drive cycle to pass the inspection you need (at least, that is the case in my state.)
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We purchased them from AutoZone and they are ac Delco brand with lifetime warranty. I mean when we purchased them the first time and the check engine light went off until we drove the X amount of time and miles then it came back on and read bank 1 sensor again so we went back to AutoZone and traded the sensor we just purchased in for another one just in case it was faulty we did this I believe 3 times the 3rd time we realized a wire was pinched and figured that was causing the code to read so fixed the wire. I really don’t believe we could get that many faulty parts from AutoZone which is why I’m saying they have to be good. We googled the drive cycle to make sure we were doing it correctly to reset the computer or monitor or whatever so I know we did the drive cycle correctly. We’re at a stand still now and don’t know what else we can do. I can’t afford to take it to a mechanic shop and spend hundreds to thousands of dollars for them to do most likely a simple fix. The truck runs and drives great so I really don’t understand why it keeps throwing those codes one we do the drive cycle. How could I get someone to reset the codes? And if they reset it would it work long enough just to pass inspection? We are in Tx.
Post the actual code. Not the definition or the description, post the code.
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A bad ECM can cause false codes, and also cause the changing of the same parts multiple times.
Tester
Did you replace the Knock sensor wiring harness or just repair the one wire??
GM has had a LOT of issues with the wiring harness to the 2 sensors, try replacing the harness… I would get the knock sensor and harness kit…
Harness…
The kit…
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And if the old knock sensors were rusty, you’ll also need to change the valley pan gasket and knock sensor grommets
Always replace the knock sensor wiring sub-harness when possible, when dealing with knock sensor circuit/performance faults (P0325/P0330).
I feel a need to ask whether you’re sure about that. “Knock” is sort of a misleading term in this context. It won’t sound like a literal “knock” - like a thumping or something. It tends to sound more like a rattle (like shaking marbles in a can), and is often mostly noticeable under load.
Certainly take in the above advice re: the wiring harnesses and whatnot. But sometimes replacing parts based on reported codes is just shooting the messenger. This engine is old enough to have hefty carbon deposits. And how old are the plugs? It also wouldn’t hurt to map out the fuel trims and make sure you’re not running lean. (Yes, that should set a code, but those car computers, “smart” as they can be, can also be pretty “dumb”).
I guess in short, when you say it isn’t “knocking” are you sure?
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You may have to try a mechanical diagnosis. If you have a noisy lifter or timing chain (if so equipped), it could trigger the knock sensor. Piston slap or a loudly rapping accessory may have that effect. I doubt that a noisy injector could cause it. Sometimes it’s not the sensor that’s the problem. If you have an egr valve, it may not be working well enough to prevent the pinging. Good luck with this one.
Is the proper octane fuel being used?
Knock sensor circuit/performance faults occur when there is no knock detected during a self-test, this usually occurs during the few minutes of a trip. The PCM is not receiving the expected signal from the knock sensors. After the fault is recorded, spark advance is normally limited to protect the engine, the operator should not notice and knocking.
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Replacing both knock sensors’ wiring harnesses seems like the next step. Hopefully that isn’t as difficult as replacing the sensors. If you feel lucky you could try just improving the ground connection between the engine block and the PCM’s ground reference , which is often the cylinder head. Use a braided ground strap from an auto parts store.
That’s not the trouble spot on this engine, George
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