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Home >> Honda >> 2000 >> CR-V SE, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 10 (Engine Controls - Self-Diagnostics - 4.3L) >> Diagnostic Trouble Code Identification >> DTC P0171: Fuel Trim System Lean Bank 1 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2000 Isuzu Hombre. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform On-Board Diagnostic II (OBD-II) System Check. See SELF-DIAGNOSTICS - INTRODUCTION article. Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Check exhaust system for corrosion, loose or missing hardware. Ensure HO2S is installed securely, and connector and harness are not contacting exhaust manifold or ignition wires. Check vacuum hoses for splits, kinks and proper routing. Check throttle body, intake manifold, and EGR valve for vacuum leaks. Check IAC, if high or unsteady idle condition exists. Check crankcase ventilation valve, spring and "O" ring for proper installation. Check for fuel contamination. Check for good VCM and sensor grounds. If any problem is found, go to step  8. If all items are okay, go to next step.
  3. Cautiously connect a fuel pressure gauge to fuel rail. Turn ignition off for 10 seconds. Turn A/C off. Turn ignition on, engine off (fuel pump should run for about 2 seconds). Cycle ignition off and on until maximum pressure is obtained. Note fuel pressure while pump is running (pressure may vary slightly when pump stops). If pressure holds at 60-66 psi (4.2-4.6 kg/cm2 ), go to next step. If pressure is not as specified, go to step  11.
  4. Start and idle engine. If fuel pressure drops 3-10 psi (0.2-0.7 kg/cm2 ), go to next step. If fuel pressure does not drop as specified, go to step  11.
  5. Perform INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If an injector problem is found, go to step  9. If injectors are okay, go to next step.
  6. Check EVAP system. See DTC P0440: EVAP SYSTEM . If an EVAP system problem is found, go to next step. If EVAP system is okay, go to DIAGNOSTIC AIDS .
  7. Repair EVAP system. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. LT FUEL TRIM value should decrease to less than 158, ST FUEL TRIM value should decrease to less than 180. If FUEL TRIM values are as specified, go to step  10. If values are not as specified, see DIAGNOSTIC AIDS .
  8. Repair faulty items found in step  2 as necessary. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. LT FUEL TRIM value should decrease to less than 158, ST FUEL TRIM value should decrease to less than 180. If FUEL TRIM values are as specified, go to step  10. If values are not as specified, go to step  3.
  9. Replace faulty fuel injector(s) as necessary. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. LT FUEL TRIM value should decrease to less than 158, ST FUEL TRIM value should decrease to less than 180. If FUEL TRIM values are as specified, go to next step. If values are not as specified, go to step  6.
  10. DTC P0171 is intermittent. If any additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, go to next step.
  11. Rich condition does not exist. If driveability problem still exists, see appropriate TROUBLE SHOOTING - NO CODES article.
  12. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0171. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step  2.
  13. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
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