LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0172: Fuel Trim System - Rich >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
    2. NOTE: If any DTCs are set other than DTC P0172, refer to affected DTCs before proceeding with this diagnostic. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  2. Install a scan tool. Review the Freeze Frame/Failure Records and record displayed data for this DTC. Select Fuel Trim Data parameter. Start engine and observe the Fuel Trim Index. Does the scan tool indicate that the Fuel Trim Index is less than -42? If yes, go to next step. If no, see DIAGNOSTIC AIDS  .
  3. Start engine. Allow engine to reach operating temperature. Put transmission in Park or Neutral position. Turn off all of the accessories. Allow engine to operate at idle. Observe Manifold Absolute Pressure (MAP) sensor parameter with scan tool. Is MAP sensor parameter within 19-42 kPa? If yes, go to next step. If no, go to DTC P0105: MAP/TP SENSOR CIRCUIT - INSUFFICIENT ACTIVITY  .
  4. Start and operate engine at idle. Observe O2S parameters with a scan tool. Does scan tool indicate that the values are within 200-800 mV? If yes, go to next step. If no, go to step  6 .
  5. Turn engine off. Visually and physically inspect vacuum hoses for splits, kinks and proper connections. Check for collapsed or restricted air intake duct. Check for dirty or restricted air filter, or for objects blocking throttle body. Did you find and correct the condition? If yes, go to step  8 . If no, go to next step.
  6. Turn engine off. Inspect O2S for proper installation. Ensure electrical connectors and wires are secured and not contacting the exhaust system. Test for continuity between the signal circuit and the low reference circuit. Did you find and correct the condition? If yes, go to step  8 . If no, diagnose fuel system. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L SONOMA & S10 PICKUP article.
  7. Inspect for excessive fuel in crankcase and evaporative emissions control system. Check fuel pressure regulator for proper operation. Ensure that all injectors are functioning properly. Did you find and correct the condition? If yes, go to next step. If no, check for an engine mechanical problem.
    8. NOTE: After repairs, use scan tool Fuel Trim Reset function in order to reset the Long Term Fuel Trim.
  8. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Does the DTC run and pass? If yes, go to next step. If no, go to step  2 .
  9. Using scan tool, observe stored information and capture information. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
scientia non olet · About LEMON Manuals