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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 41 (Engine Controls - Self-Diagnostics - Quest) >> Diagnostic Tests >> DTC P0137-P0140: Rear Heated Oxygen Sensor >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Loosen and retighten engine ground bolts. See Figure. If diagnosing for DTC P0140, go to step  3. If diagnosing for DTC P0137, DTC P0138 or DTC P0139, start engine and warm to normal operating temperature. Turn ignition off. Disconnect MAF sensor harness connector located near air cleaner. Start engine and let it idle for at least 5 seconds. Turn ignition off and reconnect MAF sensor harness connector. Go to next step.
  2. Ensure first trip DTC P0100 is set. Clear DTCs. Start engine and let it idle for at least 10 minutes. Recheck for DTCs. If DTC P0171 or DTC P0172 is present and engine is hard to start, perform diagnosis for DTC P0171 or DTC P0172. See DTC P0171 OR DTC P0172: FUEL INJECTION SYSTEM FUNCTION . If DTC P0171 or DTC P0172 is not present and engine is not hard to start, go to next step.
  3. Turn ignition off. Disconnect rear HO2S harness connector located under vehicle, on crossmember. Disconnect ECM harness connector. See Figure. Check continuity between ECM harness connector terminal No. 56 (Brown wire) and rear HO2S harness connector terminal No. 2 (White wire). See Figure and Fig 1 . Continuity should exist. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  4. Connect ECM harness connector. Check continuity between ground and rear HO2S harness connector terminal No. 3 (Black wire). Continuity should exist. Also, check circuit for short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
    5. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  5. Reconnect all harness connectors. Drive vehicle at a speed of more than 43 MPH for 2 consecutive minutes. Stop vehicle and leave engine running. Measure voltage between ground and ECM terminal No. 56 (Blue wire) by backprobing. While observing voltage, quickly increase engine speed to 4000 RPM at least 10 times. If voltage increases to more than .56 volt at least one time, go to step  7. If voltage does not increase to more than .56 volt, go to next step.
  6. Idle engine for 10 minutes and recheck voltage. If voltage decreases to than .54 volt at least once, go to next step. If voltage does not decrease to less than .54 volt at least once, drive vehicle and coast from 50 MPH with transmission in Drive with overdrive turned off. If voltage still does not decrease to less than .54 volt at least one time, replace rear HO2S and retest system.
  7. Turn ignition off. Disconnect Gray, 12-pin connector F-3 located in engine compartment, on right side of firewall. Check continuity between ground and connector F-3 terminal No. 5. See Fig 2. Continuity should exist. Also, check circuit for short to voltage. See WIRING DIAGRAMS article. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  8. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Identifying Rear HO2S Connector Terminals (Component Side)
G99A03536Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Identifying Connector F-3 Terminals
G99C50452Courtesy of NISSAN MOTOR CO., U.S.A.
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