Open circuit

If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- Front HO2S terminal A and PCM terminal 2AG
- Front HO2S terminal B and PCM terminal 2AC
- Front HO2S terminal C and PCM terminal 2G
- Front HO2S terminal D and main relay terminal E
Fig 1: Identifying Front HO2S Connector Terminals
Courtesy of MAZDA MOTORS CORP.

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