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DTC P0051: Left Front Ho2S Heater Circuit Low: Testing

NOTE: Record freeze frame data. Check for service bulletins and on-line information.
  1. Turn ignition off. Disconnect left front HO2S. Check connectors for damaged terminals and corrosion. If problem is not present, go to next step. If problem is present, repair as necessary and go to step  7 .
  2. Measure resistance between left front HO2S connector terminals "A" and "B". If resistance is 5.0-6.8 ohms, go to next step. If resistance is not 5.0-6.8 ohms, replace left front HO2S and go to step  7 .
  3. Turn ignition on. Measure voltage in Black/White wire between ground and left front HO2S harness connector terminal "A". See WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit in Black/White wire between left front HO2S harness connector terminal "A" and main relay harness connector terminal "D". Go to step  7 .
  4. Turn ignition off. Disconnect PCM connector. PCM is mounted to passenger floor, behind glove box. Check PCM harness connector and PCM terminal No. 94 for damaged terminals and corrosion. See Figure . If problem is not present, go to next step. If problem is present, repair as necessary and go to step  7 .
  5. Check continuity in Orange wire between ground and left front HO2S harness connector terminal "B". If continuity is not present, go to next step. If continuity is present, repair short to ground in Orange wire between left front HO2S harness connector terminal "B" and PCM harness connector terminal No. 94. Go to step  7 .
  6. Connect breakout box to PCM harness connector. Leave PCM disconnected. Check continuity between left front HO2S harness connector terminal "B" and breakout box terminal No. 94. See Figure . If continuity is present, go to next step. If continuity is not present, repair open on Orange wire between left front HO2S harness connector terminal "B" and PCM harness connector terminal No. 94. Go to next step.
  7. Reconnect all components. Using scan tool, clear DTC. Start engine and allow to reach operating temperature. Check for DTC P0051. If DTC P0051 is not pending, go to next step. If DTC P0051 is pending, replace PCM and go to next step.
  8. Perform after repair procedure. See AFTER REPAIR PROCEDURE  . If DTC is not present, testing is complete. If any DTC is present, go to appropriate test for diagnosis and repair.
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