# knock sensor



## Kain420 (Dec 8, 2001)

I don't have a bently and I already searched.....

I have a 2009 jetta 2.5l with a bad knock sensor. Even giving the dealer the vin number, they could not tell me which of two possible cables it is. the longer green one or shorter gray. Any ideas and do you have to pull the manifold like some other models to get to it.


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## Blkzilla (Jul 24, 2008)

They are on the back of the block and are relatively easy to get to once you have the car on jack stands. 

2 - 16mm bolts to remove the axle heat shield
3 - 10mm bolts to remove the heat shield. A short extension makes it a little easier to remove the top two.
2 - 13mm bolts to remove the knock sensors

The sensors are $40 - $60 each. I just replaced both of mine.

I've read that the torque spec of the knock sensors is critical. I believe they are supposed to be torqued to 20nm (15ft.lb.).


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## [email protected] (Aug 18, 2011)

Blkzilla said:


> ... I've read that the torque spec of the knock sensors is critical. I believe they are supposed to be torqued to 20nm (15ft.lb.).


Yes, you are correct the tightening spec is 20Nm and if they're not torqued down to spec, they will malfunction.


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