1G Code 31: Knock Sensor

[nolimits]

After removing balance shafts, new lifters & valve stem seals, and new timing belt, the car runs great...but I'm getting a code 31 a few minutes after start-up. S-AFC II shows 0-3 knock on idle and up to 9 mid-throttle while driving. Is the sensor itself likely bad or am I overlooking something?

 

[Kevin90GSX]

Could be phantom knock. If its senseing knock youd think its fine but if your getting a code saying knock sensor wouldnt that mean yes it is a bad sensor?

It cant hurt to replace it.

 

[Newlogics]

Originally posted by nolimits
After removing balance shafts, new lifters & valve stem seals, and new timing belt, the car runs great...but I'm getting a code 31 a few minutes after start-up. S-AFC II shows 0-3 knock on idle and up to 9 mid-throttle while driving. Is the sensor itself likely bad or am I overlooking something?

The only two situations, when knock sensor with throw a CEL are:

a) The is no reading.
b) Bad ground.

In your case, there is obviously a reading, so ground is your problem.
Screw the sensor out, and clean block mating surface with a wire brush. Also clean sensor side. I've gone through that.

Make sure sensor is screwed in. Mine is hand-tight. If memory serves, it's about 4ft-lbs of torque.

 

[LightningGSX]

I have noticed if you jack up the engine(too much) when doing repairs or mods you can yank the wires right out of the knock sensor.