Diagnosis & Repair Procedure
WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
- Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE under SELF-DIAGNOSTIC SYSTEM. Check for DTCs during KOEO and KOER self-test. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If DTC P0135 is present, go to next step. If DTC P0135 is not present, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
- Turn ignition off. Disconnect front HO2S connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step 9 . If connector terminals are okay, go to next step.
- Measure resistance between front HO2S Brown wire and Black/White wire terminals at sensor. If resistance is about 6 ohms (non-California emission equipped vehicle; about 3.3 ohms on California emission equipped vehicle), go to next step. If resistance is not as specified, replace front HO2S and go to step 9 .
- Turn ignition on. Measure voltage between ground and front HO2S harness connect terminal "C" (Black/White wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/White wire. See WIRING DIAGRAMS article. Go to step 9 .
- Measure voltage between ground and front HO2S harness connector terminal "D" (Brown wire). If battery voltage is not present, go to next step. If battery voltage is present, repair short to power in Brown wire. See WIRING DIAGRAMS article. Go to step 9 .
- Turn ignition off. Check for continuity between ground and front HO2S harness connect terminal "D" (Brown wire). If continuity is not present, go to next step. If continuity is present, repair short to ground in Brown wire. See WIRING DIAGRAMS article. Go to step 9 .
- Disconnect PCM connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step 9 . If connector terminals are okay, go to next step.
- Check for continuity of Brown wire between HO2S harness connector terminal "D" and PCM harness connector terminal No. 93. See Figure . If continuity is present, go to next step. If continuity is not present, repair open in Brown wire. See WIRING DIAGRAMS article. Go to next step.
- Reconnect all connections. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Perform KOEO and KOER self-test. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If DTC P0135 is present, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If DTC P0135 is not present, go to next step.
- Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE under SELF-DIAGNOSTIC SYSTEM. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.