ECD SYSTEM, Diagnostic DTC:P1605

DTC Code DTC Name
P1605 Rough Idling

DESCRIPTION

This DTC is stored when the speed of a specific cylinder becomes low and the idle speed becomes unstable. 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.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P1605

Rough Idling

When the accelerator pedal is fully closed and the engine is idling, the speed of a specific cylinder is low for 2 to 10 seconds (1 trip detection logic).

  • Injector assembly

  • Injector compensation code

  • Fuel leak

  • Glow system

  • Intake system leakage

  • Intake system blockage

  • EGR system

  • Throttle valve system

  • Suction control valve

  • Low quality fuel

  • Fuel filter element assembly air bleed problem

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

  • Engine assembly

  • ECM

Does not come on

DTC stored
Table 1. Related Data List

DTC No.

Data List

P1605

  • Target Idle Engine Speed

  • Engine Speed

  • MAP

  • MAF

  • Coolant Temp

  • Battery Voltage

  • Engine Speed of Cyl #1 (to #4)

  • Intake Air

  • Target Common Rail Pressure

  • Fuel Press

  • Common Rail Pres Sens 2

  • Target Pump SCV Current

  • Injection Feedback Val #1 (to #4)

  • Injection Volume

  • Actual Throttle Position

  • Target EGR Position

  • Actual EGR Valve Pos.

  • EGR Close Lrn. Status

  • EGR Close Lrn. Val.

  • Glow Control Unit Duty

CAUTION / NOTICE / HINT

Tip:

  • 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 rough idling.

    As the DTC can be stored as a result of certain user actions, even if the DTC is output, if the customer makes no mention of problems, clear the DTC 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.

  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 assembly malfunction.

      3. Glow plug controller 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 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.

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 DTCs and freeze frame data.

      Powertrain > Engine > Trouble Codes

      Tip:

      This freeze frame data shows the actual engine conditions when the engine idling problem occurred.

    Result

    Proceed to

    NEXT
    NEXT

  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.

      Powertrain > Engine > Trouble Codes

      Result

      Result

      Proceed to

      DTC P1605 is output

      A

      DTC P1605 and other DTCs are output

      B
      Tip:

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

    B

    GO TO DTC CHART

    Click hereClick here

    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.

      Table 2. Rough Idle #1 to #4

      Judgment of Data List Values

      Problem Cause

      Diagnosis Note

      Rough Idle #1 to #4 in the freeze frame data is ON

      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.

      Tip:

      When there are temporary changes in the injection characteristics, the malfunction may not be indicated by the value for Injection Feedback Val in the freeze frame data.
      Table 3. Injection Feedback Val #1 (to #4)

      Judgment of Data List Values

      Problem Cause

      Diagnosis Note

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

      Injector assembly

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

    Result

    Proceed to

    NEXT
    NEXT

    GO TO ROUGH IDLING OR EXCESSIVE ENGINE VIBRATIONS

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