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  #1  
Old 04-05-2023, 11:07 PM
Big Kas Big Kas is offline
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Join Date: Mar 2020
Location: Rochester
Posts: 59
Default Knock sensor- Bodge Job *sigh*

So my Ver 1 WRX has had an intermittent fault over the past year, every now again it would throw up a CEL, and the morse code would be the Knock Sensor fault.

It was intermittent maybe once or twice every few months and I largely ignored it as the car wasnt being driven hard.

However last time I drove it I went over a hard pothole..CEL comes on, restart, its off again. On my way back hit another pothole it comes on again, both times now for the knock sensor.

Ok ordered a knock sensor, went to change and realised that someone in this cars past has broken or torn the knock sensor wire and decided to twist tie another wire to the broken cable, cover it in tape, and then also hot glued the other end into the old knock sensor connector (you cant make this stuff up sometimes)

That explains why it was coming on over bumps, bad connection was getting jolted around.

So ive ordered some new wire and some crimps to do a proper job, however heres what im not sure on.... I know certain sensors which work on or generate super low current/voltage need shielded cable to stop interference. Im no wiring wizz but id assume the ecu has a shielded ground reference connection on the chassis somewhere, BUT im not sure if the single wire Knock Sensor also needs a shielded cable , anyone have thoughts?

Worst case I will buy somw shielded cable, OR visit the kitchen for some aluminium foil haha
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Old 05-05-2023, 12:03 PM
BIG"E"'s Avatar
BIG"E" BIG"E" is offline
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It sounds like you are on the case.
I hope you get it sorted.
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Keep it on the black stuff and leave the pit boards alone
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  #3  
Old 05-05-2023, 01:21 PM
Big Kas Big Kas is offline
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Join Date: Mar 2020
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Ok so fitted the new knock sensor, with new wire and proper crimps, CEL is now off and seems to be staying off.

Didnt use shielded cable, just regular car wire. However the original knock sensor cable (the unbroken half) is shielded and runs into the main loom as a shielded cable. Hopefully the shielding is only important in the loom as the external wire doesnt have any other electrical wires in close proximity.

Lets see how it lasts but hopefully thats job done for now !
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