Front HO2S circuit open/short inspection (sensor)

1. Disconnect the PCM connector.
2. Disconnect the front HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

Open circuit 

• If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
  • HO2S terminal A and PCM terminal 2AG
  • HO2S terminal B and PCM terminal 2AA

Short circuit 

• If there is continuity, there is a short circuit. Repair or replace the wiring harness.
  • HO2S terminal A and body ground
  • HO2S terminal A and power supply
  • HO2S terminal B and power supply
    Fig 1: PCM Connector Terminal Identification

    Courtesy of MAZDA MOTORS CORP.