MAZDA6 (2.3L)
WARNING: This page is about a different car, the 2003 Mazda Protege5, 2003 Mazda Protege, 2003 Mazda MX-5 Miata, 2003 Mazda MPV, and 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
- Voltage Inspection
Warm engine to normal operating temperature. Allow engine to idle. Disconnect HO2S 4-pin harness connectors (front or rear). Connect analog voltmeter test leads to HO2S 4-pin connector terminals "A" and "B". See Fig 1. Increase engine RPM to 3000 until voltmeter reads about 0.5-0.7 volt. Ensure voltmeter needle moves while increasing or decreasing engine speed suddenly several times. See HO2S VOLTAGE SPECIFICATIONS table. If voltmeter needle moves as specified, but PID value voltage readings are out of specification, check for open or short circuit between PCM and HO2S. Go to next step. If voltmeter needle does not move with engine speed, replace HO2S. - Open Circuit Inspection
Disconnect appropriate PCM 30-pin harness connector. Check for continuity between following terminals:- Front HO2S 4-pin harness connector terminal "A" and PCM 30-pin harness connector terminal No. 1AB (Black wire).
- Front HO2S 4-pin harness connector terminal "B" and PCM 30-pin harness connector terminal No. 2H (Brown wire).
- Rear HO2S 4-pin harness connector terminal "A" and PCM 30-pin harness connector terminal No. 1Y (White/Blue wire).
- Rear HO2S 4-pin harness connector terminal "B" and PCM 30-pin harness connector terminal No. 2H (Brown wire).
If continuity is present, go to next step. If continuity is not present, repair open circuit in suspect wire or replace wire harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.
- Short Circuit Inspection
Disconnect PCM 104-pin harness connector. Check for continuity between following terminals:- Front HO2S 4-pin harness connector terminal "A" (Black wire) and body GND.
- Front HO2S 4-pin harness connector terminal "A" (Black wire) and power supply.
- Front HO2S 4-pin harness connector terminal "B" (Brown wire) and power supply.
- Rear HO2S 4-pin harness connector terminal "A" (White/Blue wire) and body GND.
- Rear HO2S 4-pin harness connector terminal "A" (White/Blue wire) and power supply.
- Rear HO2S 4-pin harness connector terminal "B" (Brown wire) and power supply.
If continuity is present, repair short circuit in suspect wire or replace wire harness.
- HO2S Heater Resistance Inspection
Allow sensor to cool to room temperature. Disconnect front or rear HO2S 4-pin harness connector. Measure resistance between front HO2S 4-pin connector terminals "C" and "D". See Fig 1. Resistance reading should be 3.0-3.6 ohms at 68°F (20°C). Measure resistance between rear HO2S 4-pin connector terminals "C" and "D". See Fig 1. Resistance reading should be 5-7 ohms. If resistance reading is not as specified, replace suspect HO2S. If HO2S is okay but PID value is out of specification, check for open or short circuit. Go to next step. - Open Circuit Inspection
Check for continuity between following terminals:- Front HO2S 4-pin harness connector terminal "C" and main relay 4-pin harness connector terminal "C" (White/Red wire).
- Front HO2S 4-pin harness connector terminal "D" and PCM 30-pin harness connector terminal No. 4A (White/Black wire).
- Rear HO2S 4-pin harness connector terminal "C" (White/Red wire) and ground.
- Rear HO2S 4-pin harness connector terminal "D" (White/Black wire) and power supply.
- Rear HO2S 4-pin harness connector terminal "D" (White/Black wire) and ground.
If continuity is present, go to next step. If continuity is not present, repair open circuit in suspect wire or replace wire harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.
- Short Circuit Inspection
Check for continuity between following terminals:- Front HO2S 4-pin harness connector terminal "A" (Black wire) and ground.
- Front HO2S 4-pin harness connector terminal "A" (Black wire) and power supply.
- Front HO2S 4-pin harness connector terminal "B" (Brown wire) and power supply.
- Rear HO2S 4-pin harness connector terminal "A" (White/Blue wire) and ground.
- Rear HO2S 4-pin harness connector terminal "A" (White/Blue wire) and power supply.
- Rear HO2S 4-pin harness connector terminal "B" (Brown wire) and power supply.
If continuity is present, repair short circuit to ground in suspect wire or replace wire harness as necessary.
HO2S VOLTAGE SPECIFICATIONS
| Application | Voltage |
|---|---|
| Acceleration | 0.5-1.0 |
| Deceleration | 0-0.5 |