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 83 (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 2002 GMC Sonoma and 2002 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. Operate engine at idle. Using scan tool, observe O2S parameters. Does the scan tool indicate that the values are within 200-800 millivolts and fluctuating? If yes, go to next step. If no, go to step  5.
  4. Turn engine off. Check vacuum hoses for splits, kinks, and proper connections. Check collapsed or restricted air intake duct. Check for dirty or restricted air filter. Check for objects blocking throttle body. Did you find and correct the condition? If yes, go to step  7. After no, go to step  6.
  5. Turn ignition off. Check O2S for proper installation. Ensure harness connectors and wires are secured and not contacting exhaust system. Did you find and correct the condition? If yes, go to step  7. If no, diagnose fuel system.
  6. Check for excessive fuel in crankcase. Check EVAP control system. Test fuel pressure regulator for proper operation. Ensure that all injectors are functioning properly. Perform fuel injector balance test. See BASIC FUEL SYSTEM CHECK (GASOLINE) in appropriate BASIC DIAGNOSTIC PROCEDURES article. Did you find and correct the condition? If yes, go to next step. If no, check for mechanical engine problem.
    NOTE: After repairs, use the scan tool Fuel Trim Reset function in order to reset the long term fuel trim.
  7. 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.
  8. 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