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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 Federal models, 1/2 HO2S is located in exhaust pipe behind catalytic converter. On 4.0L Calif. models, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L models, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.
  1. Turn ignition on. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed or displayed count is not "0", go to step  6 .
  2. Turn ignition off. Disconnect 1/2 HO2S connector. Turn ignition on, with engine off. Using scan tool, actuate HO2S HEATER TEST. Using a voltmeter, measure voltage between ground and Violet/White wire (Calif. models) or Orange/Dark Green wire (Federal models). If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open in HO2S heater voltage input circuit between power distribution center and 1/2 HO2S. See WIRING DIAGRAMS article.
  3. Turn ignition off. Using ohmmeter, measure resistance between ground and Black wire at 1/1 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.
  4. Measure resistance between Violet/Orange wire and Black wire (Calif. models) or White wire (Federal models) at 1/2 HO2S connector (component side). If resistance is 50 ohms or less, go to next step. It resistance is more than 50 ohms, replace 1/2 HO2S.
  5. At this time, PCM is assumed to be defective. Replace PCM.
  6. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle 1/2 HO2S sensor connector and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.
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