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DTC P0141: 1/2 O2 Sensor Heater Failure: Testing

NOTE: 1/2 HO2S may also be referred to as a downstream oxygen sensor. On models with Federal emissions, 1/2 HO2S is located behind catalytic converter. On models with Calif. emissions, 1/2 HO2S is 1ocated in front exhaust pipe below front mini-catalytic converter.
  1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0141 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0141 or displayed count is not "0", go to step  3 .
  2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/2 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/2 HO2S voltage for 3 minutes. If voltage stays at 0.4-0.6 volt, go to next step. If voltage does not stay at 0.4-0.6 volt, go to step  7 .
  3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 1/2 HO2S connector. Measure resistance between Violet/Orange and Black wires at 1/2 HO2S connector (component side). If resistance is not 4-7 ohms, replace 1/2 HO2S. If resistance is 4-7 ohms, 1/2 HO2S heater element is okay. Go to next step.
  4. Measure resistance between ground and Black wire at 1/2 HO2S harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire (heater ground circuit). See WIRING DIAGRAMS article.
  5. Ensure 1/2 HO2S is still disconnected. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Violet/Orange wire at 1/2 HO2S harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in Violet/Orange wire (power circuit to 1/2 HO2S heater).
  6. At this time, PCM is assumed to be defective. Replace PCM.
  7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/2 HO2S voltage while wiggling connectors and wiring harness from 1/2 HO2S to Powertrain Control Module (PCM). PCM is located in engine compartment on left front fender, near radiator support. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
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