What is the purpose of a knock unit and what does it do does it pertain to the oil
Aug 7, 2009 at 8:58 AM
MMPRINCE4000
✓Experienced Mechanic
8,548 POSTS
If you are talking about a knock sensor? It screws into a water jacket and like a microphone listens for any pinging or pre-ignition. If it detects is it will tell PCM to retard timing anywhere from 1-15 degrees, to prevent damage to engine.