I am having trouble with one of two knock sensors on the 6.1 hemi. I consistantly get values of approx 0.4370 volts from the PCM via DashHawk for knock sensor 1. Knock sensor 2 is always at zero. Because of the supposed knocking, the PCM retards timing (knock retard) by approx 105 degrees, although the timing decrease only happen in the morning (at first start up). All subsequent start ups throughout the day I don't experience any timing retard, although knock sensor 1 still indicates knocking. I have gone thru multiple tanks of gas, from different vendors, but nothing has changed. I even switched my 180 degree thermostat back to stock, thinking that the tstat may have been the problem... still nothing. Anyways, so I am starting to think I may have a bad knock sensor...so my question is, where exactly are the knock sensors? I'd like to replace them as a first step before I take the car in to be serviced.

I am sorry to hear about the issue. Normally, I believe they are located under the intake manifold.

Side of engine, below exhaust manifold.

thanks guys

timster - i know it's a long shot, but please make sure all of your exahust parts are tight - given how close it is to exahust manifold, I am curious if it's picking up some knocking coming from the exhaust system.

Has anyone removed the knock sensors but left them plugged in?