ECD SYSTEM(w/ Urea SCR System), Diagnostic DTC:P1605

DTC Code DTC Name
P1605 Rough Idling

DESCRIPTION

This DTC is stored if the combustion state of any cylinder is unstable.

Using the GTS, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P1605 Rough Idling When idling with the accelerator pedal released and the vehicle stopped, this item detects when the combustion is unstable from the sudden changes in engine speed between the cylinders. Detection for 2 to 10 seconds according to the combustion state (1 trip detection logic).

  • Injector assembly

  • Injector compensation code

  • Fuel leak

  • Glow system

  • Intake air system leakage

  • Intake system blockage

  • EGR system

  • Throttle valve system

  • Pre-stroke control valve

  • Low quality fuel

  • Fuel filter element assembly air bleed problem

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

  • Engine assembly

  • ECM

 - DTC stored
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)

    (Output only when the "Check the Cylinder Compression" Active Test is performed)

  • Intake Air

  • Target Common Rail Pressure

  • Common Rail Pressure

  • Injection Feedback Val #1 (to #4)

  • Injection Volume

  • Actual Throttle Position

  • Target EGR Valve Pos

  • Actual EGR Valve Pos

  • EGR Close Lrn. Val.

  • Rough Idle #1 (to #4)

  • Plural Cylinders Rough Idle

CAUTION / NOTICE / HINT


  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 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 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 conventional DTCs for components, circuits and systems, DTC P1605 is used to estimate the malfunctioning area from problem symptoms and freeze frame data in response to symptoms such as "rough idling", "strong engine vibrations", etc. Such problem symptoms can occur even in the following conditions:


      • Driving with long-stored fuel (fuel that has remained in the tank for long periods of time)

      • Using fuel not acclimated to the climate during a change of seasons

      • Temporarily using low-quality fuel (fuel that contains water or has poor fuel properties)

    • 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. READ 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 / Trouble Codes.

    4. Record the stored DTC and freeze frame data.


      Powertrain > Engine > Trouble Codes

      Tech Tips

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

      Tech Tips

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


    B

    GO TO DTC CHART Click 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.

      Rough Idle #1 (to #4)
      Judgment of Data List Values Problem Cause Diagnosis Note Proceed to
      Any of 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.

      Tech Tips

      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.

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

      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.

      		 A
      Plural Cylinders Rough Idle
      Judgment of Data List Values Problem Cause Diagnosis Note Proceed to
      Plural Cylinders Rough Idle in the freeze frame data is ON

      • EGR system

      • Diesel throttle system

      • Fuel supply pump assembly

      • Low-quality fuel

      		 When EGR Rate Differential (Actual-Target) increases by more than 30%, there may be a malfunction in the EGR system. B
      When there is data stored that indicates that Common Rail Pressure is low compared to Target Common Rail Pressure, there may be a malfunction in the fuel pressure control system, such as in the fuel supply pump assembly. C
      When data indicating that MAP is low (50 kPa or less) is stored, there may be a stuck closed malfunction in the diesel throttle system or EGR valve. -

    A

    GO TO INSPECT INJECTOR COMPENSATION CODE (ROUGH IDLING OR EXCESSIVE ENGINE VIBRATIONS) Click here

    B

    GO TO CHECK DATA LIST (ACTUAL EGR VALVE/TARGET EGR VALVE DIFFERENTIAL) (ROUGH IDLING OR EXCESSIVE ENGINE VIBRATIONS) Click here

    C

    GO TO CHECK DATA LIST (COMMON RAIL PRESSURE AND TARGET COMMON RAIL PRESSURE) (ROUGH IDLING OR EXCESSIVE ENGINE VIBRATIONS) Click here