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Test NTC-7B - Checking Oxygen Sensor Switching

NOTE: Perform TEST NTC-7A before proceeding. For connector terminal ID, see CONNECTOR IDENTIFICATION DIRECTORY. For component location see wiring diagram in the WIRING DIAGRAMS article.
  1. Allow engine to idle. Inspect engine for vacuum leaks. Repair vacuum leaks as necessary and perform TEST VER-2A. If no vacuum leaks exist, go to next step.
  2. Using scan tool, read HO2S signal voltage. If voltage is 0.1 volt or more on all HO2S, go to step 6). If voltage is less than 0.1 volt on any HO2S, go to next step.
  3. Turn ignition off. Disconnect suspected HO2S connector. inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A. If connector and terminals are okay, go to next step.
  4. Disconnect Powertrain Control Module (PCM) connectors. Inspect connectors and terminals. Repair connectors and terminals as necessary and perform TEST VER-2A. If connectors and terminals are okay, go to next step.
  5. Using an external ohmmeter, check resistance between ground and HO2S connector, HO2S signal circuit (for appropriate wire color, see HO2S SIGNAL CIRCUIT IDENTIFICATION table). If resistance is less than 5 ohms, repair short to ground in HO2S signal circuit and perform TEST VER-2A. If resistance is 5 ohms or more, replace HO2S and perform TEST VER-2A.
  6. Turn engine off, ignition on. Using scan tool, reset adaptive fuel memory. Start engine, and allow it to idle for 3 minutes. Using scan tool, read HO2S state. If HO2S state is switching, repair is complete. Perform TEST VER-2A. If HO2S state is not switching, perform TEST NTC-22A.
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