Knock sensors?

05lq4 · April 30, 2020

Question: How often to knock sensors go bad? Do they or is it just the harness?

Im coming up on 160,000miles on my 05 lq4 and I'm getting ready to do gaskets on my heads and intake. I see suggestions to do the knock sensor wire harness while i got it apart. Which im fine with. But im always about budget. I wont use anything but OEM and the sensors are spendy. If thats all i was doing i could see spending the $$. But things are starting to add up quick.

Any advice is appreciated. Thanx in advance!

txab · April 30, 2020

I think it would be prudent to change the KS, since they will be completely accessible. The general problem with these was the wells that they sit in would fill with water and ruin the KS

davester · April 30, 2020

Yeah, they can get water damaged (seems to be worse for some people, particularly those that wash their engine regularly).

It's a tradeoff, as you can't see if if looks like the wiring harness should be replaced without taking everything apart, and then you have to pay more to get the part quickly, vs buying it in advance with other parts for less money.

And it is much more expensive to replace later, as you've got to (well, I would) replace the intake manifold gaskets again to do the wiring harness separately.

Edited April 30, 2020 by davester

kstruckcountry · April 30, 2020

Check online for good prices on the ACDelco sensors and harness. I use RockAuto. If you go ahead and do them now you won't regret it. I did mine 100k miles ago, and they've been good since. I did coat the rubber sensor caps with high temp silicone and built a v-shaped "dam" in front of each sensor.

I originally used (overpriced) parts from O'Reilly's due to getting the code a day before leaving for a road trip. That was a mistake, it threw the code again while I was on the trip and I got to pull the intake again to replace them with ACDelco that I ended up paying less for online once I got back. Lesson learned. No refund from O'Reilly's for the faulty sensors either, of course.

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tigers2007 · May 4, 2020

There is an eBay seller that sells both knock sensors and harness for cheap. One word of caution though, eBay and Amazon are breeding grounds for counterfeit parts that look exactly alike. I stick with RockAuto or my local AutoValue store.