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DTC P2177

DETECTION CONDITION AND POSSIBLE CAUSE (DTC P2177 - LF, L3)

DTC P2177 Fuel system too lean at off idle
DETECTION CONDITION 
  • The PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT and the sum total of these fuel trims exceed preprogrammed criteria. PCM determines that fuel system is too lean at off-idle.

    • Diagnostic support note 

  • This is a continuous monitor (Fuel system).
  • The MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.
  • FREEZE FRAME DATA is available.
  • DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Misfire
  • Front HO2S deterioration
  • Front HO2S heater malfunction
  • MAF sensor malfunction
  • Pressure regulator (built-in fuel injection pump) malfunction
  • Fuel pump malfunction
  • Fuel filter clogged or restricted
  • Fuel leakage on fuel line from fuel delivery pipe and fuel pump
  • Leakage exhaust system
  • Purge solenoid valve improper operation
  • Purge solenoid valve malfunction (stuck open)
  • Purge solenoid hoses improper connection
  • Air suction in intake-air system
  • Insufficient engine compression
  • Variable valve timing control system improper operation.
  • PCM malfunction
DIAGNOSTIC PROCEDURE CHART

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Fuel system related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE OR STORED DTCS 
  • Turn the ignition switch off, then to the ON position (Engine off).
  • Verify related pending code or stored DTCs.
  • Is other DTC present?
 Yes If misfire DTC is present, go to Step 8.
If other DTC is present, go to the applicable DTC inspection.
(See DTC TABLE ).
No If driveability concern is present, go to Step 8.
If not, go to the next step.
4 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA 
  • Is DTC P2177 on FREEZE FRAME DATA?
 Yes Go to the next step.
No Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5 VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION SWITCH TO THE ON POSITION/IDLE) 
  • Access APP1, APP2, ECT, MAF, TP and VSS PIDs using WDS or equivalent.
  • Is there any signal that is far out of specification when the ignition switch is at the ON position and the engine runs?
 Yes Inspect the sensor and excessive resistance in related wiring harnesses.
Repair if necessary.
Then go to Step 17.
No Go to the next step.
6 VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION 
  • Inspect the same PIDs as Step 5 while simulating FREEZE FRAME DATA condition.
  • Is there any signal which causes drastic changes?
 Yes Inspect the sensor and related wiring harnesses repair or replace it.
Then go to Step 17.
No Go to the next step.
7 VERIFY CURRENT INPUT SIGNAL STATUS OF FRONT HO2S 
  • Access O2S11 for P2177 PID using WDS or equivalent.
  • Check PID under following accelerator pedal condition (in PARK (ATX) or NEUTRAL (MTX).
  • Is PID reading normal?
    • Less than 1 mA  when accelerator pedal is suddenly depressed (rich condition).
    • More than 1 mA  just after release of accelerator pedal (lean condition).
 Yes Go to the next step.
No Visually inspect for any gas leakage between the exhaust manifold and the front HO2S.
Then go to Step 17.
8 VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR 
  • Connect the WDS or equivalent to the DLC-2.
  • Start the engine.
  • Access the MAF PID.
  • Verify that the MAF PID changes quickly according to engine speed.
  • Is the PID normal?
 Yes Go to the next step.
No Replace MAF/IAT sensor, then go to Step 17.
9 INSPECT FOR EXCESSIVE AIR SUCTION OF INTAKE AIR SYSTEM 
  • Visually inspect for loosen, cracks or damages hoses on intake-air system.
  • Is there any malfunction?
 Yes Repair or replace source of air suction, then go to Step 17.
No Go to the next step.
10 INSPECT PURGE SOLENOID OPERATION  Yes Go to the next step.
No Repair or replace the malfunctioning part according to inspection result, then go to Step 17.
11 INSPECT FUEL LINE PRESSURE  Yes Go to Step 12.
No If the fuel pressure is too high, replace fuel pump unit, then go to Step 17.
If the fuel line pressure is low, go to the next step.
12 INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE 
  • Visually inspect fuel line for any leakage.
  • Is fuel leakage found?
 Yes Replace suspected fuel line, then go to Step 17.
No Inspect for foreign materials or stain inside fuel filter (low-pressure).
If for foreign materials or stain inside fuel filter (low-pressure), clean of fuel tank and filter.
Then go to Step 17.
13 INSPECT IGNITION SYSTEM 
  • Perform spark test.

    (See SPARK TEST ).

  • Is strong blue spark visible at each cylinder?
 Yes Go to the next step.
No Repair or replace the malfunctioning part according to spark test result, then go to Step 17.
14 INSPECT ENGINE COMPRESSION  Yes Go to the next step.
No Implement the engine overhaul for repairs, then go to Step 17.
15 INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION  Yes Go to the next step.
No Repair or replace the malfunctioning part according to inspection results, then go to Step 17.
16 INSPECT FUEL INJECTOR OPERATION 
  • Remove the fuel injector.
  • Inspect the fuel injector (resistance, injection amount).

    (See FUEL INJECTOR INSPECTION ).

  • Is the fuel injector normal?
 Yes Go to the next step.
No Replace the fuel injector, then go to the next step.
17 VERIFY TROUBLESHOOTING OF DTC P2177 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Perform the KOER self-test or the PCM Adaptive Memory Produce Drive Mode.

    (See OBD-II DRIVE MODE ).

  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION ).
No Go to the next step.
18 VERIFY AFTER REPAIR PROCEDURE  Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No Troubleshooting completed.
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