Diagnosis & Repair Procedure
WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect all applicable harness connectors. Repair as needed. Turn ignition on. Access ECM harness connector. ECM is mounted in front of center console, under radio. Using voltmeter, backprobe applicable ECM harness connector. Measure voltage between ground and terminal No. 3M.
- Voltage should be 0-1.0 volt with engine idling at normal operating temperature. If voltage is within specification, go to step 5). If voltage is not within specification, go to next step.
- Turn ignition off. Disconnect left front oxygen sensor harness connector. Using ohmmeter, backprobe ECM harness connector. Check continuity between terminal "A" on left front oxygen sensor harness connector and terminal No. 3M on ECM connector. If continuity does not exist, repair Yellow wire. If continuity exists, go to next step.
- Inspect fuel injectors, mass air flow sensor, engine coolant temperature sensor. See appropriate SYSTEM/COMPONENT TESTS - 2.3L article. Replace as needed. Inspect fuel pressure regulator. See appropriate BASIC TESTING - 2.3L article. Replace as needed. Inspect spark plugs and air intake system. Repair or replace as needed. If all items are okay, replace left front heated oxygen sensor.
- Erase DTCs. See CLEARING CODES in SELF-DIAGNOSTIC SYSTEM section. If DTC resets, replace ECM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.