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DTC P0141 (RO2_H) - Rear O2S Heater Circuit Malfunction

  1. Install SSM. Retrieve DTCs. If DTC P0141 and P0135 are not present at the same time, go to step 3). If DTC P0141 and P0135 are present at the same time, go to next step.
  2. Turn ignition off. Disconnect ECM harness connector. Check resistance between ECM harness connector terminal No. 42 and chassis ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is 5 ohms or less, repair poor contact in ECM connector. If resistance is greater than 5 ohms, repair open in harness between ECM and coupling connector, open in harness between coupling connector and engine ground terminal, poor contact in rear O2S connector, poor contact in rear O2S connector harness connector or poor contact in coupling connector.
  3. Turn ignition off. Set SSM to function mode F33 to read rear O2S heater current indication. Start and warm engine to normal temperature. If reading is less than 0.2 amp, go to next step. If reading is 0.2 amp or greater, repair poor contact in ECM and rear O2S harness connector.
  4. Start and idle engine. Using DVOM connected to chassis ground, backprobe ECM connector terminal No. 37. If voltage is 1.0 volt or less, go to step 6). If voltage is less than 1.0 volt while wiggling ECM harness and connector, repair poor contact in ECM connector. If voltage remains 1.0 volt or less, go to next step.
  5. Disconnect rear O2S connector. Backprobe ECM harness connector terminal No. 37. If voltage is 1.0 volt or less, replace ECM. If voltage is greater than 1.0 volt, check for short in harness between ECM and rear O2S connector. If circuit is okay, replace ECM.
  6. Turn ignition off. Disconnect rear O2S harness connector. Turn ignition on. Check voltage between rear O2S harness connector terminal No. 2 and chassis ground. If voltage is 10 volts or greater, go to next step. If voltage is less than 10 volts, repair poor contact in connector or open circuit in harness between main relay and rear O2S.
  7. Turn ignition off. Check resistance between rear O2S harness connector terminals No. 1 and No. 2. If resistance is greater than 30 ohms, replace rear O2S. If resistance is 30 ohms or less, repair open in circuit between rear O2S and ECM harness connector, poor contact in rear O2S connector, poor contact in ECM connector or poor contact in rear O2S connecting harness connector.
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