ECD SYSTEM (w/o DPF), Diagnostic DTC:P1605

DTC Code DTC Name
P1605 Rough Idling

DESCRIPTION

If the idle speed drops or becomes unstable when the engine is running at idle with a low load, this DTC is stored. This DTC is also stored if the vehicle runs out of fuel. Be sure to check whether there is enough fuel in the fuel tank before inspection.

P1605
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
- The engine speed drops to less than 400 rpm (1 trip detection logic).
  • Injector assembly

  • Injector compensation code

  • Fuel leak

  • Glow system

  • Intake air system leakage

  • Intake air system blockage

  • EGR system

  • Throttle valve system

  • Suction control valve

  • Low quality fuel

  • Fuel filter element sub-assembly air bleed problem

  • Accessory problem (A/C, generator, etc.)

  • Engine assembly

  • ECM

Related Data List
DTC No. Data List
P1605
  • Engine Speed

  • MAP

  • MAF

  • Coolant Temp

  • Battery Voltage

  • Engine Speed of Cyl #1 (to #4)

  • Intake Air

  • Target Common Rail Pressure

  • Common Rail Pressure

  • Target Pump SCV Current

  • Injection Feedback Val #1 (to #4)

  • Injection Volume

  • Actual Throttle Position

  • Target EGR Valve Pos

  • Actual EGR Valve Pos

  • EGR Close Lrn. Val.

INSPECTION PROCEDURE


  1. In order for idling to be stable, glow system operation, fuel system operation and compression sufficient to maintain the target idling speed are necessary.

  2. Glow system


    1. The following malfunctions may be present in the glow system.


      1. Engine coolant temperature sensor malfunction.

      2. Glow plug malfunction.

      3. GLOW relay malfunction.

  3. Fuel system


    1. The following malfunctions may be present in the fuel system.


      1. Fuel leakage.

      2. Problem with injector assemblies.

      3. Problem with fuel supply pump assembly.

      4. Air in fuel pipe.

  4. Engine assembly


    1. The following malfunctions may be present in the engine assembly.


      1. Insufficient compression.

        Tech Tips


        • In contrast to normal malfunction diagnosis for components, circuits and systems, DTC P1605 is used to determine the malfunctioning area from the problem symptoms and freeze frame data when the user mentions problems such as engine stall.

          As these DTCs can be stored as a result of certain user actions, even if these DTCs are output, if the customer makes no mention of problems, clear these DTCs without performing any troubleshooting and return the vehicle to the customer.

        • If any other DTCs are output, perform troubleshooting for those DTCs first.

        • Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

        • When confirming the freeze frame data, be sure to check all 5 sets of freeze frame data.

PROCEDURE


  1. DTC OUTPUT (RECORD STORED DTC AND FREEZE FRAME DATA (PROCEDURE 1))


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    4. Record the stored DTC and freeze frame data.

      Tech Tips

      This freeze frame data shows the actual engine conditions when air fuel ratio too rich trouble occurred.


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  2. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P1605)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    4. Read the DTCs.

      Result
      Result Proceed to
      P1605 is output A
      P1605 and other DTCs are output B

      Tech Tips

      If any DTCs other than P1605 are output, troubleshoot those DTCs first.


    B
    A
  3. DETERMINE CAUSE OF PROBLEM (CHECK FREEZE FRAME DATA)


    1. Determine the cause of the problem based on the freeze frame data recorded in Procedure 1.

      Injection Feedback Val #1(to #4)
      Judgment of Data List Values Problem Cause Diagnosis Note

      Any of Injection Feedback Val #1 to #4 in the freeze frame data is more than 3.0 mm3/st

      Injector assembly

      If the cylinder that displays Rough Idle ON also has a value of more than 3.0 mm3/st for Injection Feedback Val, improper combustion in that cylinder is suspected.


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