Diagnosis & Repair Procedure
- Ensure FREEZE FRAME PID data has been recorded. Check service bulletins. Go to next step.
- Disconnect FHO2S. Inspect front O2 sensor and harness connector terminals. If no problem is found, go to next step. If problem is found, repair as necessary and go to step 8
.
- Check resistance of FHO2S between terminals "C" and "D". See Fig 1
. Resistance should be 5.6 ohms (California emissions) or 15.7 ohms (Federal emissions). If resistance is as specified, go to next step. If resistance is not as specified, replace front heated O2 sensor and go to step 8
.
- Turn ignition on. Check voltage at FHO2S harness connector terminal "C" (Black/Blue wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open or short in circuit between ignition switch and FHO2S. Go to step 8
.
- Inspect PCM and harness connector terminals. If no problem is found, go to next step. If problem is found, repair as necessary and go to step 8
.
- Check continuity between FHO2S harness connector terminal "D" (Light Green/Red wire) and ground. If continuity is not present, go to next step. If continuity is present, repair short to ground. Go to step 8
.
- Connect breakout box to PCM harness connector. Leave PCM disconnected. Check continuity of Light Green/Red wire between FHO2S harness connector terminal "D" and PCM connector terminal No. 94. If no problem is found, go to next step. If problem is found, repair as necessary and go to next step.
- Reconnect all connectors. Turn ignition on. Clear DTC from memory. Warm engine to operating temperature. Recheck for DTCs. If same DTC is present, replace PCM. If same DTC is not present, go to next step.
- Clear DTC from memory. Recheck for DTCs. If any DTC is present, diagnose and repair DTC. If no DTCs are present, test is complete.
Courtesy of MAZDA MOTORS CORP.