What are the chances of a knock sensor in a 1998 Mazda Millenia 2.3l engine go bad?

Question

What are the chances of a knock sensor in a 1998 Mazda Millenia 2.3l engine go bad?

Answer 1

... is a 10 ten year car, the heat, the water, vibration over time will damage anything on the car

you are lucky considering that part gets bad after 10 years of use

Answer 2

i have seen a few cases where it has gone bad.  it will throw a code, P0325.  you can check it by ohm'ing it at the connector, 560 kohm with a cold engine.   part number is KJ01-18-921A, mazda sugg list is 158.84.  the good news is you can find them on ebay occasionally for much less.  however, that is the ONLY good news.  a knock sensor is like a tiny microphone.  it is filled with some silicone like stuff, and over time, it kinda oozes out.  to get at it, all kinds of stuff has to come off.  like the compressor itself.  which means you gotta pull the intake.  the intercoolers, the battery, the serpentine belt for the compressor.  the crossover connection tube for the injector rails.  it gets better.  the sensor is a wierd size, and you will need a special socket.  it is very much like a slotted o2 sensor socket, but a different size.  torque is critical on this.  over torque it, and it will mess up the reading to the pcm.  undertorque it, and it will come out, and you get to do it all over again.  what are the ramifications?  if the pcm sees a bad knock sensor, it throws the code, and the ce lite comes on.  then, the pcm pulls timing and boost.  iow, you lose a lot of power, cause pcm is afraid of knock, so it wont let the engine run like it should.   another caveat.  although the ebay sensor is cheaper, i have never seen it.  if i do the job on my car, because of the intense labor involved, i wouldnt take a chance on an aftermarket sensor.   if it was YOUR car, and you brought me the sensor, no problem.  i guarantee my labor, but if that rascal is bad, you gotta pay me again to change it.