SFI SYSTEM(w/ EGR System), Diagnostic DTC:P1605

DTC Code DTC Name
P1605 Rough Idling

DESCRIPTION

When the engine is idling stably under a low load, if the idle speed drops or becomes unstable, this DTC will be stored.

Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P1605 Rough Idling After 5 seconds or more elapse after starting the engine, with the engine running, the engine speed drops to 400 rpm or less (1 trip detection logic) - Does not come on DTC Stored

CAUTION / NOTICE / HINT

Tech Tips


  • In contrast to normal malfunction diagnosis for components, circuit 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 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 DTCs other than P1605 are output, troubleshoot those DTCs first.

  • Since DTC P1605 is different from other DTCs, the following procedure is shown as a reference.

  • Read freeze frame data using the GTS. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

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

    Click here

  • When confirming freeze frame data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.

  • Try to operate the vehicle under the conditions recorded in the freeze frame data which were present when the malfunction occurred. Confirm the data at this time and the data when the engine is idling (engine warmed up and no load) and compare these data with the freeze frame data.

  • Inspections take into account the fact that the malfunction may not have reoccurred and place emphasis on checking the vehicle conditions present at the time the malfunction occurred.

  • When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.

PROCEDURE


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


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

    5. Read the DTCs.

      Click here


      Powertrain > Engine and ECT > 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

  2. CHECK FREEZE FRAME DATA


    1. Turn the GTS on.

    2. Check the following freeze frame data to see if the engine was cold or warm when the freeze frame data was recorded.

      Confirmation Item
      Coolant Temp
      Initial Engine Coolant Temp

    3. Check the following freeze frame data to see if the vehicle was idling.

      Confirmation Item
      Engine Speed

    4. Check the following freeze frame data to see purge VSV operation when the freeze frame data was recorded.

      Confirmation Item
      EVAP (Purge) VSV
      Evap Purge Flow
      Purge Density Learn Value
      EVAP Purge VSV

    5. Check the following freeze frame data to see engine idle operating conditions recorded.

      Confirmation Item
      Throttle Position
      ISC Flow
      ISC Position
      Idle Spark Advn Ctrl #1
      Idle Spark Advn Ctrl #2
      Idle Spark Advn Ctrl #3
      Idle Spark Advn Ctrl #4
      ISC Feedback Value
      ISC Learning Value
      Electric Load Feedback Value
      Air Conditioner FB Val
      Low Revolution Control
      MAP
      EGR Step Position

    6. Check the following freeze frame data to see the engine load and electric load.

      Confirmation Item
      Calculate Load
      Electric Fan Motor

    7. Use this information to perform a simulation test.

    8. Compare the "Normal Condition" information in the Data List table (reference values) with the freeze frame data listed above and with the simulation test results to determine the problem cause.

      Result
      Result Proceed to
      The problem cause can be determined A
      The problem cause cannot be determined B

    A

    REPAIR OR REPLACE MALFUNCTIONING PARTS

    B

    CHECK FOR INTERMITTENT PROBLEMS Click here