Front HO2S Circuit Open/Short Inspection (Sensor): Notes

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

Fig 1: Identifying Front HO2S Connector Terminals
Courtesy of MAZDA MOTORS CORP.

Fig 2: Identifying Fuse Box Main Relay Connector Terminals
Courtesy of MAZDA MOTORS CORP.

Fig 3: Identifying PCM Sensor Connector Terminals
Courtesy of MAZDA MOTORS CORP.