Knock sensor
 

hi all
2007 lt2/auto, 2.4l 136000kms
having an intermittent knock sensor code.comes on for a couple hours,then disappears for days/weeks the reappears .
dealer here in canada says 2 hrs labour at $90/hr to install plus $60 for part.
says that install is more involved than it appears.
any reason for this to take longer than an hour?
i looked thru the tutorial on this site and it looks like more than i am able to do without a lift.
i use only regular gas,would a mid grade help or should the sensor be replaced.
thanks,jeff

Changing your grade of fuel will not help, although the 2.4 prefers Premium and that's what is recommended by GM for it. The crank sensor does just that, it gets a signal from a reluctor wheel on the crank and identifies its rotational position, that's how the ECM "knows" which cylinder is at TDC. So a bad crank sensor means your engine occasionally loses track of where its crankshaft is, and it sets a code. It can be a DIY job, as you've seen from the tutorial, your dealer is probably quoting the "book rate" for the job. If GM says two hours, they'll quote you two hours, even if the tech is done in an hour.

The sensor that is directly involved with and affected by your choice of gasoline grade is the "Knock Sensor" which does exactly that, it detects pre-ignition or "Knock" in the engine and retards the ignition timing accordingly. Running Regular in a 2.4 just means the timing is retarded a bit to prevent knock, and the engine isn't able to develop its full rated horsepower under certain conditions.

hi
sorry,it was the knock sensor not the crank sensor..
dohhh

Well if its a knock sensor code, you could try upgrading to Premium gasoline and seeing if the code reappears, but since it is generating a code, I doubt that would cure your problem.

On occasion I'll run a tank of Regular or Midgrade through my 2011 with a 2.4 engine and no codes are set. But depending on the octane of the Regular grade gasoline sold up in your area, it may suffer enough pre-ignition to trigger a code, but I'm skeptical about that.

As far as your dealer's labor quote, like I said earlier, they are probably quoting you the "book rate" on the job.

Knock sensor replacement - https://www.chevyhhr.net/forums/how-tutorial-library-21/how-change-2008-2-2l-knock-sensor-34865/