DTC 91: Front Heated Oxygen Sensor (Ho2S)
- Check Power Supply
Turn ignition off. Disconnect HO2S wiring harness connector. See Figure
. Turn ignition on. Measure voltage between HO2S connector terminal "C" (White/Green wire) and ground. See Fig 1
. If battery voltage is present, go to next step. If voltage is not as specified, repair harness or connectors between HO2S and fuse box.
- Check Ground Circuit
Turn ignition off. Disconnect ECM wiring harness connector. Verify harness continuity between HO2S connector terminal "A" (Yellow wire) and ECM terminal No. 115. See Fig 2
. If continuity is present, go to next step. If continuity is not present, repair harness or connectors between HO2S and ECM.
- Check Component
With ambient temperature about 77°F (25°C), measure resistance between HO2S terminal "A" and "C". Resistance should be 3.3-6.3 ohms. Verify for continuity between terminals "A" and "B" and between terminals "B" and "C". Continuity should not be present. If continuity is not as specified, replace HO2S. If continuity is as specified, go to next step.
- Disconnect ECM wiring harness connector. Check connector pins for damage or corrosion. Check all circuit connector for clean, tight fit. If fault is still present, repeat step 1).
Courtesy of NISSAN MOTOR CO., U.S.A.
Courtesy of NISSAN MOTOR CO., U.S.A.