Heated Oxygen Sensor (Ho2S): Millenia
WARNING: This page is about a different car, the 2001 Mazda Protege, 2001 Mazda Millenia, 2001 Mazda MX-5 Miata, 2001 Mazda MPV, and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
- Warm engine to normal operating temperature. Connect scan tool to DLC-2. DLC-2 is located under left side of instrument panel, right of steering column. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
- Turn ignition on. Select appropriate HO2S PID to be checked. Voltage should be .5-1.0 volt under acceleration and 0-.5 volt under deceleration. If voltage is not as specified, check wiring harness and connector between PCM and HO2S. Also check intake air system, fuel system and self-diagnostic system. Repair as necessary. If problems are not present, replace suspect HO2S.
- To test HO2S heating element on 2.5L, go to next step. To test HO2S heating element on 2.3L, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between sensor terminals "B" and "C" for front HO2S 3-pin connector or terminals "C" and "D" for rear HO2S 4-pin connector. See Fig 1 . Resistance should be about 6 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.
- To test HO2S heating element on 2.5L, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between HO2S 4-pin connector terminals "C" and "D". See Fig 2 . Rear HO2S resistance should be 6 ohms with sensor temperature at 68°F (20°C). Front HO2S resistance should be 3.3 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.