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DTC P0141: O2 Sensor 1/2 Heater Failure

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: The 1/2 O2 sensor is referred to as downstream oxygen sensor heater monitor runs during oxygen sensor cool-down period, after a hot drive cycle or when engine is shut down with ignition off. DTC may be stored in Powertrain Control Module (PCM) if downstream oxygen sensor signal voltage is different when heater is commanded on as compared to when heater is off. Possible causes are: defective downstream oxygen sensor or heater, defective Auto Shutdown (ASD) relay output circuit, or defective connectors or wiring.
  1. Turn ignition on with engine off. Using scan tool, check for DTCs. If global good trip counter is displayed and equal to zero, go to next step. If global good trip counter is not displayed and equal to zero, go to step  5.
  2. Turn ignition off. Disconnect downstream oxygen sensor connector. Downstream oxygen sensor is located on exhaust pipe, behind catalytic converter. Turn ignition on with engine off. With scan tool in SENSORS mode, actuate O2 HEATER TEST. Using voltmeter, check voltage at ASD relay Dark Green/Orange wire. ASD relay is located in Power Distribution Center (PDC). If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open Dark Green/Orange wire between ASD relay and downstream oxygen sensor. Perform TEST VER-5A .
  3. Turn ignition off. Using ohmmeter, check resistance between ground and downstream oxygen sensor connector terminal No. 2 (Black wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black wire. Perform TEST VER-5A .
  4. Check resistance between downstream oxygen sensor connector (harness side) terminals No. 1 (Dark Green/Orange wire) and No. 2 (Black wire). If resistance is 4-7 ohms, replace PCM. Perform TEST VER-5A . If resistance is not 4-7 ohms, replace downstream oxygen sensor. Perform TEST VER-5A .
  5. Inspect wiring and connectors between downstream oxygen sensor and PCM. Inspect related wiring harnesses and connectors. Refer to Technical Service Bulletins (TSBs) for related problems. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-5A .
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