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Old 04-22-2012, 03:46 PM   #1 (permalink)
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Default PO328 code questions

Was given an 03 H6 sedan with 178,000 miles and a bunch of problems. All fixed except a PO328 code. I have reset multiple times, there is no rhyme or reason as to when the code comes back, once it came back instantly, once with three monitors reset and once with 7 reset. The CEL also shut off on its own one day then came back on the next with the same code.

This car has never had the plugs replaced, obviously its on my list of things to do, I also understand that the intake needs to be pulled to replace the knock sensors. Based on the experience of you guys do you think that the random times I get the code back could be a result of bad plugs causing it and that the knock sensors actually work?

Is there any benefit to doing the plugs on an H6 with the intake off? I am trying to limit what I spend on the car, if it needs both knock sensors and plugs I can do it but at this point I need to pass inspection and do so without draining my wallet anymore.

Any help or shared experiences would be greatly appreciated!
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Old 04-22-2012, 05:27 PM   #2 (permalink)
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With 178,000 miles on the original plugs, I wouldn't be surprised if there were some problems. However, the P0328 code isn't a knock problem code as might occur if a cylinder was malfunctioning; rather, it's a diagnostic code indicating an open circuit in the knock sensor electrical connection back to the ECU.

The knock sensor has a connector going to the main engine wiring harness -- the contacts there could be poor. Also, the metal body of the sensor itself is the ground for the sensor signal and it goes through the contact between the metal body of the sensor and the engine block, so this interface could also be problematic.

Not sure how much work it is to access the knock sensors on the H6 (perhaps others can fill in), but checking the connections might be all that's needed for that intermittent knock sensor CEL.
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Old 05-20-2013, 08:07 AM   #3 (permalink)
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I know this is an old thread, but to help others here, I wanna say that my 00 OBW, 2.5, was throwing a PO328, and after pulling other knock sensors and coil packs from engines here, I found the problem to be the spark plug gap. After narrowing the gap with a couple um... precision taps against the fenderwell, car runs great, and the CEL stays off. Don't throw money into parts you might not need.
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Old 05-20-2013, 04:52 PM   #4 (permalink)
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Quote:
Originally Posted by crazycraig View Post
I know this is an old thread, but to help others here, I wanna say that my 00 OBW, 2.5, was throwing a PO328, and after pulling other knock sensors and coil packs from engines here, I found the problem to be the spark plug gap. After narrowing the gap with a couple um... precision taps against the fenderwell, car runs great, and the CEL stays off. Don't throw money into parts you might not need.
I have been saying that all along. Test it, test it, test it. Then replace.
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