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Old 11-10-2014, 07:14 PM   #1
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Knock Sensor Help

Hello Everyone,

I have a 2000 Boxster S with about 35000 miles. This vehicle was purchased about 2 months ago. There is a code for the knock sensor 1 (P0327). At the time of purchase, this code was not stored. I know, because I personally checked for any codes at the time of purchase. I don't believe this code will trigger the check engine light (MIL) but you can tell when this code sets. There is a slight loss of power. I did some investigating and by looking at the scan data the Safety Retardation goes active and the timing for all the cylinders goes retarded (negative) when the code is stored.



I did some research and a few mention the wire close to the connector being broken. Possible by rodent damage. There are a few rodent droppings on the top of the engine but they look like it has been there for awhile. Moving on, the connector/wire is not visible from the top. I can see the left side knock sensor connector but not the right side. I even tried using a video scope but gave up after 15 minutes.

Has anyone tried repairing the wire or connector? I think the wire/connector might be visible by removing the alternator but I don't know if it could be repaired in the confined space. I know removing the intake manifold would be the best choice but I would rather remove the alternator being I don't want to break all the plastic pipes that are connected to the manifold. Has anyone repaired the wire by removing the alternator only?

I will introduce my vehicle at a later date being I don't have a good picture of my car and I noticed that is more important than describing your vehicle.

Thanks for any help.

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Old 11-15-2014, 05:02 PM   #2
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I don't know if anyone is interested but here is the outcome. I decided to first check the resistance of the circuit at the ECM. The circled connector is where the knock sensor wires are.



The front circled wires are sensor 1 and the back ones are sensor 2.



Sensor 2 measured 5 M ohms and sensor 1 was open. Knowing the outcome, it would have been far easier to skip this part of the diagnosis.

I then removed the front engine cover and the problem was obvious while using a flashlight. The picture doesn't show the problem but looking below the alternator (circled) shows the problem.



The connector was broken or eaten. It is hard to tell being there are no markings on the other part of the wire.







There was enough room to do the repairs on the connector/wire with the alternator removed. Engine power is restored and it doesn't go into Safety Retardation.

Last edited by Miles1; 11-15-2014 at 05:06 PM.
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Old 11-15-2014, 08:06 PM   #3
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That is a clean-cut wire for being suspect rodent damage... Looks like someone took a pair of side cutters and cut it.
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Old 11-16-2014, 06:22 AM   #4
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Quote:
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That is a clean-cut wire for being suspect rodent damage... Looks like someone took a pair of side cutters and cut it.
Someone didn't cut it with wire cutters. I have a picture showing a cut wire but I can't find it at this time. Cut wires are a lot cleaner. I could have gotten better macro pictures but my efforts were doing the repair instead of documenting the repair.

Here is a picture of a more obvious rodent damage. This is from a BMW and for some reason, rodents like the wires at the oil level sensor. I have seen this on 4 different BMW's. I guess you could say it was the same rodent but no one knows for sure.


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Old 11-16-2014, 06:50 AM   #5
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Quote:
Originally Posted by Jager View Post
That is a clean-cut wire for being suspect rodent damage... Looks like someone took a pair of side cutters and cut it.
I'm with Jager on this one...
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Old 11-16-2014, 01:29 PM   #6
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If the alternator has been removed or replaced it could have damaged the wire. I certainly looks like a clean cut though with no fraying of the copper cores or bite marks round the insulation.

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