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Daniel Wilson
Daniel Wilson,
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Cat man, I have a code 3936-2 on a 2009 c13 cat. What is

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cat man, I have a code 3936-2 on a 2009 c13 cat. What is this code for?

Hi my name is***** will be glad to help.

The ECM has not detected the size of the DPF. The ECM is using the default size for the DPF. The power rating of the engine determines the default size. Engine power is derated. One of the following diagnostic codes is present:

3936-2 The signal indicates that the size of the DPF is not correct for the engine's power rating.
3936-3 The signal from the sensor group is above the acceptable limit.
3936-4 The signal from the sensor group is below the acceptable limit.
Once the system is powered via the keyswitch a delay of approximately 15 seconds will occur before the code appears.

Greater than 100 hours
Or
Equal to 100 hoursThe ECM has not detected the size of the DPF. The ECM is using the default size for the DPF. There is no 3936-x diagnostic code. There is no derate.
Flashing software that has a personality module release date that is newer than OCT 07 can cause the condition. No troubleshooting is required.

XXXX********** (1) N/A The ECM has automatically detected the size of the DPF. There is no 3936-x diagnostic code. There is no derate. No troubleshooting is required.

XXXX1234567890 (1) N/A The serial number of the DPF has been manually entered into the ECM. There is no 3936-x diagnostic code. No troubleshooting is required.

Test Step 1. Program the Serial Number for the DPF into the Engine ECM

  1. Program the entire serial number for the DPF into the engine ECM.

Note: The serial number typically has 14 characters. If the serial number contains less than 14 characters enter zeroes to the end of the serial number in order to complete the programming.

Expected Result:

The 3936-x code is cleared.

Results:

  • The code clears. - Return the vehicle to service.STOP

     

  • The code does not clear. -

    Repair: Perform the following procedure.

    1. Verify that all of the characters for the serial number are correct. Try to program the serial number again.

     

    1. Contact your local technical communicator for Caterpillar on-highway engines if the ECM will not accept the correct serial number.

    STOP

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