H26 - Check HO2S For Short to Ignition Run Circuit

Key "OFF".
Heated Oxygen Sensor (HO2S) disconnected.
Measure resistance between KEY PWR circuit and HO2S SIG circuit at the connector (refer to schematic). H - Test Schematic

Is resistance greater than 10,000 ohms?

Yes -- For Diagnostic Trouble Codes (DTC) 137, 173 and 177: Go to H27. H27 - Attempt to Generate DTC 136, 172, or 176

For DTCs 171, 174, 175, 178:

Manifold Absolute Pressure (MAP) sensor: Go to H28. H27 - Attempt to Generate DTC 136, 172, or 176

Mass Air Flow (MAF) sensor: Go to H30. H30 - HO2S Check


No -- Replace HO2S. Drive vehicle 5 miles/55 mph. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)