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DTC P0140-A: O2S 1/2 Stays At Center

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
  1. For O2 sensor/model identification see O2 SENSOR 1/2 IDENTIFICATION  table. Using scan tool, read DTCs. If Global Good Trip displayed is zero, go to next step. If Global Good Trip displayed is not zero, go to step  4.
  2. Using scan tool, read FREEZE FRAME data. Ensure hex code matches DTC on scan tool. Hex code should be 81. If hex code corresponds to scan tool display, go to next step. If hex code does not correspond to scan tool display, repair DTC using FREEZE FRAME data. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  3. Drive vehicle under FREEZE FRAME data conditions. Using scan tool, read DTCs. If Global Good Trip displayed is zero, perform test procedure again. After performing test procedure again, perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If Global Good Trip displayed is not zero, DTC is not present at this time. Using scan tool, erase DTCs. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  4. Disconnect O2S 1/2 connector. Turn ignition on. Connect a DVOM between O2S 1/2 connector (harness side) signal circuit and ground. See O2S 1/2 CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE)  table. If voltage is 4.5 volts or less, go to next step. If voltage is more than 4.5 volts, replace O2S 1/2. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  5. Using a voltmeter, backprobe O2S 1/2 signal circuit between PCM connector terminal No. 51 and ground. See PCM CONNECTOR WIRE IDENTIFICATION  table. If voltage is 4.5 volts or less, go to next step. If voltage is more than 4.5 volts, repair open O2S 1/2 signal circuit between PCM connector terminal No. 51 and O2S 1/2 connector. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  6. Turn ignition off. Disconnect PCM connector. Inspect PCM connector for damage and cleanliness. If PCM connector is okay, replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If PCM connector is not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
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