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DTC P0137: 1/2 O2 Sensor Shorted To Ground: 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 fir DTC P0137 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0137 or displayed count is not "0", go to step  8 .
  2. Start engine and allow it to idle. Using scan tool, read 1/2 HO2S voltage. If voltage is less than 0.16 volt, turn ignition off and go to next step. If voltage is 0.16 volt or more, go to step  8 .
  3. Disconnect 1/2 HO2S connector. Start engine and allow it to idle. Using scan tool, read 1/2 HO2S voltage. If voltage is less than 0.16 volt, go to next step. If voltage is 0.16 volt or more, replace 1/2 HO2S.
  4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment on left front fender, near radiator support. Measure resistance between ground and Tan/White wire at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/White wire between PCM and 1/2 HO2S.
  5. Measure resistance between Tan/White and Brown/Yellow wires at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/White and Brown/Yellow wires are shorted together. Repair wiring as necessary.
  6. Measure resistance between Tan/White and Black wires at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/White and Black wires are shorted together. Repair wiring as necessary.
  7. At this time, PCM is assumed to be defective. Replace PCM.
  8. 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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