DTC P0136: Heated O2 Sensor (Ho2S) No. 2 CKT Malfunction

NOTE: Before replacing HO2S No. 2, inspect sensor for contamination. If contamination is present, determine cause and repair before installing a new HO2S No. 2.

Connect scan tool to Data Link Connector (DLC). Drive vehicle for at least 5 minutes at 35 MPH or greater with engine coolant temperature at 158°F (70°C) or greater. Observe OXYGEN SENSOR B1 S1 parameter on scan tool while sharply increasing engine RPM and returning to idle. If voltage is about zero volts, go to next step. If voltage varies between zero and one volt, check for an intermittent problem. See TESTS W/O CODES article. If voltage is greater than one volt, go to step 3).
Turn ignition off. Disconnect HO2S No. 2 harness connector. Start engine. Using a voltmeter, measure voltage between terminals No. 1 and 2 of HO2S No. 2 while sharply increasing engine RPM. See Figure . If voltage varies between 0.1 and 0.9 volt, go to step 4). If voltage is not as specified, replace HO2S No. 2. Retest system.
Turn ignition off. Disconnect HO2S No. 2 harness connector. Turn ignition on. Observe OXYGEN SENSOR B1 S1 parameter on scan tool. If voltage is about zero volts, replace HO2S No. 2. If voltage is not as specified, check Red wire between PCM and HO2S No. 2 for a short to power. Repair as necessary. If wire is okay, replace PCM. Retest system.
Check Red wire between PCM and HO2S No. 2 for an open, short to ground or short to Gray/Red wire. Check Red wire between PCM and HO2S No. 2 for an open or poor connection. Repair as necessary. If wires and connections are okay, replace PCM.