3. Check HO2S Signal Waveform
- Reconnect the HO2S and ECM connectors.
- Warm up the engine to normal operating temperature.
- Using a Hi-Scan (Pro), monitor the HO2S signal waveform.
Do the rear HO2S signals fluctuate between 0V and 1V?
Yes: Proceed with ECM problem procedure.
No: Replace HO2S.