- Check Ground Circuit Turn ignition off. Disconnect rear HO2S and ECM harness connectors. Using an ohmmeter, check continuity between ground and rear HO2S connector terminal No. 3 (Black wire). If continuity exists, go to next step. If continuity does not exists, repair fault in Black wire.
- Check Input Signal Circuit Turn ignition off. Using an ohmmeter, check continuity as follows: Between ECM harness connector terminal No. 56 and rear HO2S connector terminal No. 2 (White wire). Continuity should exist Between ground and ECM harness connector terminal No. 56 or rear HO2S connector terminal No. 2. Continuity should not exist
If continuity is not as specified, repair fault in circuit. If continuity is as specified, loosen and retighten engine ground screws. Disconnect ECM and HO2S wiring harness connector. Check terminals for damage or corrosion. Repair if necessary and perform FINAL CHECK . If fault is still present, replace rear HO2S.
