Heated Oxygen Sensor: Miata
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 Mazda Protege5, 2002 Mazda Protege, 2002 Mazda Millenia, 2002 Mazda MX-5 Miata, and 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
- Voltage Inspection
Warm engine to normal operating temperature. Disconnect HO2S 4-pin harness connector. Connect voltmeter between ground and HO2S 4-pin connector terminal "A". See Fig 1 . Run engine at 3000 RPM until voltmeter indicates 0-1 volts. Ensure voltage changes within specification when engine RPM is increased or decreased several times. See HO2S VOLTAGE (MIATA) table. If voltage reading does not change as specified, replace HO2S. If HO2S is okay but PID value is not as specified, check for open or short circuit. See WIRING DIAGRAMS article. Go to next step.HO2S VOLTAGE (MIATA)Application Volts Acceleration 0.5-1.0 Deceleration 0-0.5 - Open Circuit Inspection
Turn ignition switch off. Disconnect 31-pin harness connector. Check for open circuit. Check for continuity between following terminals:- PCM harness connector terminal "4W" and front HO2S harness connector terminal "A" (Blue wire). See Fig 2 and Fig 3 .
- PCM harness connector terminal "4O" and front HO2S harness connector terminal "B" (Black/Red wire), through common connector.
- PCM harness connector terminal "4AA" and rear HO2S harness connector terminal "A" (Red wire).
- PCM harness connector terminal "4O" and rear HO2S harness connector terminal "B" (Black/Red wire), through common connector.
If continuity is not present, repair or replace wire harness as necessary. Go to next step.
- Short Circuit Inspection
Check for continuity between ground and following PCM terminals:- PCM 31-pin harness connector terminal "4W" (front HO2S). See Fig 2 .
- PCM 31-pin harness connector terminal "4AA" (rear HO2S)
If continuity is present, repair or replace wire harness as necessary.