LEMON Manuals: Even more car manuals for everyone
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 P0172: Fuel Trim System Rich 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) 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 air intake duct for restrictions. Check for plugged air filter. Check IAC, if low or unsteady idle condition exists. Check throttle body for coking and IAC passages for blockage. Check fuel pressure regulator for proper operation. See FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article. Check TP sensor for loose or missing mounting bolts. Using scan tool, read TP sensor voltage while slowly opening throttle from closed (0.20-0.74 volt) to wide open (4 volts). A steady throttle movement from a stop should cause TP sensor voltage to increase smoothly as throttle is opened. If any of these items isolate or require repair, go to step  8. If all items are okay, go to next step.
  3. 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. 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.
  5. Check HO2S for silicon contamination (powdery, white deposit). If contamination is evident, go to step  12. If contamination is not evident, go to next step.
  6. Check for any EVAP system DTCs retrieved in step  1. See SELF-DIAGNOSTICS - INTRODUCTION article. If any undiagnosed EVAP system DTCs were displayed, diagnose affected DTCs. Repair EVAP system as necessary. After repair, go to next step. If no EVAP system DTCs were stored, see DIAGNOSTIC AIDS .
  7. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT FUEL TRIM value increases to greater than 100 and ST FUEL TRIM value increases to greater than 94, go to step  10. If values are not as specified, go to DIAGNOSTIC AIDS .
  8. Repair 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 increase to greater than 100, ST FUEL TRIM value should increase to greater than 94. If FUEL TRIM values increase as specified, go to step  10. If values do not increase as specified, go to step  3.
  9. Replace fuel injector(s) as necessary. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT value increases to greater than 100 and ST fuel value increases to greater than 94, go to next step. If values do not increase as specified, go to step  5.
  10. DTC P0172 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. Replace HO2S (bank 2 sensor 1). After replacing sensor, go to next step.
  13. 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 P0172. 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.
  14. 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.
scientia non olet · About LEMON Manuals