Nissan Repair: Knock Sensor on 99 Pathfinder, louisiana mississippi, mississippi alabama

Question
My 1999 Pathfinder (6 cylinder, 2WD) check engine light has come on and my mechanic says that it's #325, a "Knock Sensor" light.  Mechanic said it will cost $387 to replace the sensor due to removing the upper & lower intake.  But, after reading online how knock sensors work, I wonder if the sensor needs replacing or if there is a reason why the sensor is sending the signal.

Here's what happens:  I have to make a 12 hour drive occassionally.  6 hours one way then turn around and drive 6 hours back(Louisiana/Mississippi/Alabama heat).  The last two times I have made this drive, my Pathfinder will race at times while driving.  The mechanic said that the sensor was trying to "change the timing of the engine."  

This never happens when I am driving locally or even for a couple hours.  I was wondering, should the sensor be replaced (what if it's not faulty?)or should I try using a higher octane fuel?  (Currently using low octane due to $$$).  And should I have my spark plugs check? Any suggestion?

Thank you!

Wendy

Answer
Wendy,

You could try super unleaded and see if the code stays off.  But, if it does not the knock sensor needs to be replaced.  And, it is a pain in the tail to replace.  If the quote includes parts and labor you are getting a deal.  This is one item I dislike doing since the intake has to come off to access the sensor.