What Is Fault Code SPN 639 FMI 9? (Cummins, Freightliner)

While fault codes help you with the diagnosis, there are just too many of them. But without them, you wouldn’t know where to begin when fixing your engine.

The SPN 639 FMI 9 fault code equals Cummins 285 fault code. This translates into - Abnormal Update Rate. What that means is that the ECM either did not get the information fast enough or the information did not arrive at all.

To learn more about this fault code, just continue to read our article. It has the information you want to know about so that you can solve the problem faster. All it takes is the right diagnosis and you should be on the road again before you know it.

Fault Code SPN 639 FMI 9 Freightliner


It is all about communication. When you see this error code then you know something is not reporting to the ECM in a timely manner and the ECM is upset about this failure to communicate.

The source of the problem could be the 500K 1939 splice packs in the OEM harness. The splice packs open when they get hot and then cause all sorts of havoc with your gauges as well as the ABS light.

Sometimes you can just wiggle the harness after pulling to the side of the road and everything will return to normal. The problem with receiving this code is that your ECM may set several other codes at the same time.

You have to go through all the codes and fix them before getting the SPN 639 FMI 9 code cleared.

What is SPN 639 FMI 2 Cummins?


The code is basically going to be the same as the Freightliner. There is a failure to communicate and you may experience some engine trouble. Most likely, you will see the amber check engine light illuminated when you get this code.

If you go to our complete Cummins fault code article, you will see at the bottom of page 2 this code. It is Cummings 285 and it is the last code on that page. When you get to it, you will see these words:

J1939 Network #1, Primary Vehicle Network (previously SAE J1939 Data LinK)” and “SAE J1939 Multiplexing PGN Timeout Error - Abnormal update Rate.”

Unfortunately, you have to go to another datasheet to get the proper repair procedures:

-Validate repairs by performing a key cycle, then starting and idling the engine for at least 1 minute.

After the diagnostic passes, the ECM will turn off the amber CHECK ENGINE light and change the fault code status to INACTIVE.

Use the “Reset All Faults” command in the diagnostic tool to clear active and inactive fault codes and to turn off the malfunction indication lamp (MIL) for OBD applications.” (https://f01.justanswer.com/TomcM28/becab306-f1bf-48f0-9cfd-5778182d36f7_285.pdf)

The problem with the complete Cummins fault code list is that it may not register more than one FMI fault code with each Cummings fault code. There are at least 4 more FMI codes that will appear with the SPN 639.

You have to have access to other data sheets to find the complete information for every SPN FMI combination.

SPN 639 FMI 5


This code is telling you that you have either an open circuit or a short in the circuit somewhere. We can not tell you exactly where that problem is and you will either have to do some testing yourself or go to a dealer or mechanic’s shop to resolve it.

One thing you should know about these fault codes is that if you see an ABS fault code, there will be no FMI code following it. The ABS system does not come with an FMI sequence.

Even if you have a fault code reader, you may not be able to pull up the codes as updates are often done making the reader incapable of finding the right codes. Those updates can be very expensive to get.

When you start getting the SPN 639 code, the following action is to be expected:

- The ECM turns on the amber CHECK ENGINE light as soon as the diagnostic fails.

The multiplexed device WILL NOT operate”

Then the source for this and other SPN 639 codes can be:

OEM VECU is sending a message saying the accelerator pedal is not available for multiplexing.

OEM VECU is not set up to send multiplexed component messages.

Damaged SAE J1939 datalink connection between the OEM VECU and ECM”

SPN 639 FMI 7


This FMI code, like FMI 5, does not show up on the lists that we have come across but both do show up on your screens. In this case, FMI 7 is telling you that there is no communication between the ECM and other modules.

According to one mechanic, that source may be a blown ECM fuse. This fuse is located somewhere along the wiring between the battery and the ECM. What we can tell you is that this code may appear with several other codes.

What that means is that you have a lot of work to do to finally get to the source of the problem if it is not the fuse. The message may say ‘no abs’ next to this code so check that area of your system after the fuse.

Some Final Words

Tracking down the correct meaning of all the SPN FMI codes can be more work than the repair work that needs to be done. It is just the way these codes are published and be prepared to find that some FMI codes will be missing from different lists.

When this happens to you, you have two choices, You can continue searching for the right code sequence or simply go to a mechanic that has the updated information. All SPN 639 codes are related to communication so that will eliminate a lot of your work.

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