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Dodge Cummins 6.7 Owners, Do You Know Why Your Engine Light Is On?

Courtesy of Good Sam Emergency Road Service (ERS)

Fault indicators are your vehicles way of letting you know there is a malfunction in one of the onboard systems. The check engine, or service engine soon, light can illuminate for various reasons—some are immediate concerns, but most are emissions related and will not affect performance or cause damage.

Your Cummins diesel engine is being constantly monitored by a various sensors and circuits. These sensors produce signals that are interpreted by the engine computer or engine control module (ECM). The engine computer expects to see certain signal ranges. If the signal ranges are not as expected, a fault will be logged. These signals are monitored constantly by the Cummins ECM.

If a malfunction has occurred, but is not present on the malfunction indicator lamp (MIL), the ECM will store an inactive fault or history code. If the malfunction is current, an active fault code is stored, and the MIL will illuminate or flash. A flashing MIL indicates a serious malfunction, and you should cease operation as soon as safely possible.

How do you know if it is safe to continue operation?

You have to communicate with the ECM, and ask it to tell you what is happening. You can do this by pulling the fault codes. Here’s how:

Procedure for retrieving fault codes on Dodge 6.7 Cummins trucks:

  1. Select “total miles” on the trucks odometer, not trip.
  2. Insert ignition key.
  3. Move the key from LOCK TO OFF, THEN PAUSE.
  4. Move ignition key to ON/RUN.
  5. Move ignition key BACK TO OFF.
  6. Move ignition key to ON/RUN.
  7. Move ignition key BACK TO OFF.
  8. Move ignition key to ON/RUN and STOP THERE!

The Key cycles from OFF to ON/RUN should be done in less than 5 seconds.

You then can read the codes on the truck’s odometer. (See complete list below.)

Once you have pulled the codes, contact your Good Sam ERS, and ask to speak to a technician. The tech will be able to advise you on the possibilities and offer further guidance. Once you know the problem, you will have a better idea if you want to work on the repairs yourself or take it to a qualified professional.

ISB fault codes:
A complete list of all Dodge Cummins ISB (5.9 & 6.7L)

Written by your Good Sam RV technician JD


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