Knock Sensor replacement made easy
 

After reading a few nightmarish descriptions of the knock sensor replacement procedure, I approached this job with some reluctance last night. Most people seem to think the front sensor is very easy to replace, and the rear one requires hours of patience and the fingers of a surgeon. This is not really the case.

Remove the belt cover, the alt/ps belt, and the a/c belt. Remove the alternator from the car. Now here's the trick: remove the engine lift bracket with the compressor still attached and move it off to the side. Do not disconnect the hoses. There is enough flex in the system to move the whole assembly well out of the way. I was able to carefully wedge it against one of the radiator supports, but a bungee set-up would probably be safer. If you pulled the battery, the whole thing would probably rest right in that spot nicely.

Now you have lots of room to work, and the "rear" knock sensor actually becomes the easiest one to do. Finding the connector is still a little tricky, but you can put your whole hand in and grab the wire to wiggle it around while watching from the outside.

The whole job took me about an hour and a half, much of which was spent cleaning a mouse nest out from under my intake manifold.

I hope this helps someone out in the future. My car runs smoother now than I ever remember, so I think the knock sensor must have been failing long before it ever starting throwing a code.

Way to go, Dr. Freeman!

As I understand it, a sensor has to fail consistently before a code is stored. I think it also has to fail consistently three times in a row.

But I might be making that up. I'll try to remember to look it up when I go home for lunch.

Now I know where to bring the car when my sensors fail. Now that you have experience, I guess the job should take about 30 minutes, or two beer's worth. Very affordable.
See you on the 25th.

Ron.

Would you let me know if your gas mileage goes up? :)

I'll run a tank through and let you know what mileage I'm getting now, but I've never really paid much attention to it in the past to tell you where it is coming from.

Now I'll let you know if my gas mileage goes up.:) I replaced both knock sensors on Saturday. I followed your how -to. Thanks it was very helpfull. The a/c compressor I left alone. There are just too many bolts to remove and mess around with and it reminds be of a Chinese Puzzle. In my opinion it's not worth the time.

My engine SOUNDS so much better. I think the LH knock sensor was bad for over a year. The low frequency "thud" has gone away. :)

There is absolutely no resistance reading on the LH sensor I took out. The RH still read okay.

Hi,

You said your car had a "Thud" did it kinda sound like the cylinder was missing?

EASY ACCESS ???
 

Do you access both the knock sensors from the front ? [ Sounds like it, since you're saying you removed all these front engine parts and ended up with easier access to the rear sensor than even the front sensor?] :confused:

THANKS for the tips! :D

It was a very faint sound that was not louder than the basic engine noise. I am not sure I would say it sounded like a miss as that would always be there and would be louder or would have a random frequency to it. The noise I refre has a fixed beat. :)

Re: EASY ACCESS ???
 

I got them in from the front and my hands are not real big. Thank goodness for that. :) It was a tight fit for sure as I slid my hand between the metal vaccuum lines and the engine block.:rolleyes: Full metal contact.