Open circuit

If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- Knock sensor terminal A and PCM terminal 2U^*1 ,2Q^*2
- Knock sensor terminal B and PCM terminal 2V^*1 ,2R^*2
  
  Fig 1: PCM Connector Terminal Identification
  Courtesy of MAZDA MOTORS CORP.