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Cat Man
Cat Man, Caterpillar Engine Expert
Category: Heavy Equipment
Satisfied Customers: 8822
Experience:  23 Years Caterpillar Engine experience.
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Classic: freightliner..5 injector #3 occurences 127 & rack Actuator

Customer Question

i have a 3406E cat in a freightliner classic codes read sid:23 fmi:5 sid:3 fmi:5 injector #3 occurences 127 & rack Actuator occurences 127 . replaced injector still same codes. any ideas?
Submitted: 6 years ago.
Category: Heavy Equipment
Expert:  Cat Man replied 6 years ago.

Hi. Thanks for using JA! I will try and help you out.


Could you get me your engine serial number please? Thanks.

Customer: replied 6 years ago.
2ws10562 also where is rack actuator located?
Expert:  Cat Man replied 6 years ago.

Thanks for the information.


If possible, I would like to try and pull the flash codes from your engine. The reason is because the 2WS 3406E does not have a code 23 -5 and the engine does not have a rack actuator. Sorry.


I assume that the information that you are being given is in correct and not your fault.

Pulling the flash codes will be more accurate for diagnostics. If you have never pulled the codes, here is how to do it.



Use the following procedure to retrieve the flash codes if the engine is equipped with a diagnostic lamp:

  1. Turn the ignition key to the ON position/Engine off.
  2. Turn the cruise control ON/OFF switch to the OFF position.
  3. Move the SET/RESUME switch to either position. Hold that position until the yellow lamp begins to flash.

The yellow lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the flash code. After a two second pause, the second sequence of flashes will identify the second digit of the flash code.



Customer: replied 6 years ago.
31 &72 also engine runs smooth at idle & high rpm's skips at mid rpm's
Expert:  Cat Man replied 6 years ago.

Thanks for the information.


Code 31 is a loss of vehicle speed signal that will not cause you engine to miss at high idle.



Code 72 is a fault code on either cylinder number 1 or number 2. I wisdh I could be more specific on which cylinder the problem is on but the flash codes pairs 1&2 together with code 72.


You most likely have a failed #1 or #2 injector on your engine.