code 52 knock sensor can't pass emissions

[mrnickleye]

KS is there to sense "pinging" when the fuel is 'pre-detonating'. The computer will back the timing up until the ping is gone. It usually only happens under a load (like during the test).

Running mid-grade or premium gas helps to eliminate pinging, if yours does ping.

If your check light is on, you will fail the test (unless the guy lets you slide).