When it comes to vehicle fluids, DEF is the most recent. That means it may be harder to find top-quality DEF fluid as it is easy to make and easy to sell. Fortunately, vehicle makers have put a warning system in place to tell you when you bought low-quality DEF.
SPN 3364 FMI 2 tells you when you have “Improper Diesel Exhaust Fluid (DEF) Quality” in your DEF tank. If the quality is not between 28 and 36%, then you need to flush your tank and replaced the low-quality DEF with a better brand.
To learn more about this topic and fault code, just continue to read our article. It has the information you want to know about so you can make the right DEF buying decision. Quality counts even if it costs a bit more than the other brands.
Code SPN 1548
What is SPN 3364 FMI 2?
Cummins Fault Code SPN 3364 FMI 9
Cummins Fault Code SPN 3364 FMI 10
SPN 3364 FMI 18
Low-Quality DEF
What is SPN 3364 FMI 2?
This fault code is warning you about the quality of the DEF fluid you may have just purchased. This fault code is looking out for you as it is very hard to tell if the DEF is good or bad.
When you get this warning light, you are being told that “Improper Diesel Exhaust Fluid (DEF) Quality” is in your system. This fault code can be triggered for any number of reasons.
There are 2 main reasons why you would see this code. One is that, which has happened on more than one occasion, you accidentally put the wrong fluid in the DEF line. Some people go on automatic when they reach the pumps and open their DEF cap instead of their diesel fuel cap.
Thousands of dollars in repair work have been spent by these types of owners because of this simple mistake. It is not hard to make this mistake especially if you are sleepy and not paying attention to what you are doing.
You could blame the truck maker for the location of the DEF refueling line but that won’t do any good. The 2nd main reason you will get this warning is that the DEF you bought was already bad or of very low quality.
DEF has a very short shelf life and if you bought yours from a store that does not sell a lot of DEF then chances are it is not a good fluid to use. If you need to buy this fluid, then pick a store that keeps selling out of it in a hurry.
After you drain the DEF tank, make sure to cycle your ignition, 2 minutes on, 2 minutes off, several times to allow for mixing the new fluid with the bad. As we said, it is very hard to tell when the DEF is good or when it is bad.
Cummins Fault Code SPN 3364 FMI 9
This fault code tells you that the “DEF fluid quality sensor inactive”. When this warning code appears, you may only have 4 to 8 hours of drive time left before the engine does its 5 mph derate.
That may be enough time to get to a service station if you can find an authorized service center that will do the repair work. The repair is a simple replacement of the def level/quality sensor which is located inside the DEF tank.
When we say, if you can find a repair center that will do the work, it seems that if you have anything to do with Spartan components, many service centers will not fix your problem.
Even some that are authorized Spartan repair centers won’t touch a low-level fix as this fault code indicates. One owner had to make several calls to Spartan to find an authorized dealer that would work on their issue.
There is not much to describe about this fault code as it is a simple replacement fix that should not take a very long time to complete. The other issue that is related to this fault code is that you may have low-quality DEF in your DEF tank.
The fix for that is to drain the tank. This can be easy and it cannot be as some DEF tanks have a drain plug and others do not. The key in this repair is to make sure you bought top-quality DEF fluid as a replacement.
Cummins Fault Code SPN 3364 FMI 10
The Cummins fault code for this error code is 4277 and the Cummins fault code list we have provided in another article has this to say about it- “Aftertreatment 1 Diesel Exhaust Fluid Tank 1 Quality- Aftertreatment Diesel Exhaust Fluid Quality - Abnormal Rate of Change.
You can expect an amber light to be illuminated when this fault code is set. We have a repair sheet for this code, unfortunately, this repair sheet also lists 7 other codes at the same time.
Its repair instructions are not code-specific but there are diagrams to follow. This repair sheet does provide the names and parts numbers for the different kits you may need to solve your problem. There are no special tools needed to do this repair.
Since this specific code deals with DEF quality, chances are you will need to add top-quality DEF or replace the current fluid in the DEF tank. The other repair suggestions should be looked at as well as you may have those codes listed on your reader.
Two of those 7 other codes are an SPN 3364 types but with different FMI numbers (4 & 18). The latter number we will discuss in the next section.
The SPN 3364 FMI 4 is equal to Cummins 1685 and it is for:
“Aftertreatment Diesel Exhaust Fluid Quality Sensor Circuit -
Voltage Below Normal or Shorted to Low Source - Amber
Warning Light”
You will need to be able to check the voltage on your DEF system to make sure nothing is wrong there or to find the short, etc.
SPN 3364 FMI 18
The Cummins equivalent to this SPN FMI code is 3367 and it is found on page 20 of the comprehensive guide we have published on this website. When you see this code it stands for the following problem:
“Aftertreatment 1 Diesel Exhaust Fluid Tank 1 Quality- Aftertreatment Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range - Moderate Severe Level”
The initial repair is to check to see if the DEF is between 28 and 36%. If not, then you have to flush the old out and replace it with new. However, if it is, you have up to 14 other steps to take to solve this problem.
There are numerous opportunities in those steps to release the vehicle as long as the conditions are met according to this data sheet.It is not easy to know when the DEF has gone bad.
One of the signs is if the display or your storage area is in direct sunlight or not. If it is, that will shorten the fluid’s lifespan. It also has to be stored in cooler conditions that are greater than 23 degrees F and less than 68 degrees F.
Low-Quality DEF
Since these error codes deal strictly with DEF, it is important to know how this fluid can go bad. There are different ways, most may be accidental, that lower the quality of this fluid.
The first way would be water contamination. The ratio is supposed to be 32.5% of Urea and 67.5% of water. Any more or less than this figure and your DEF sensor will set a code.
The quality of the DEF is not where it is supposed to be. It is what is called water contamination. Then storage is a big issue. Normally, if stored under the conditions stated above, you have a 2-year window to use the DEF.
But if the fluid is stored above the 68 degrees F maximum, that lifespan goes down to 1 year. Then someone may use the empty DEF storage containers for other fluids, for example- oil.
If they do not thoroughly clean those containers and put DEF back into them, you will get oil contamination. Then if you pour that DEF into your DEF tank, you could ruin your SCR and create damage that will not be covered by your warranty.
Gas or diesel in your DEF tank will do the same thing, causing thousands of dollars in repair bills you need to pay out of pocket.
Some Final Words
Watch your DEF system. Do not go into automatic when refilling the tank or use cross-contaminated storage containers. You need to keep the quality of the DEF at the proper levels to avoid costly repairs or a 5 mph derate.
Sometimes, the sensor is just bad. Do not assume it is always the fluid causing the fault code. Check your sensor as well to make sure it is working right. The same code comes up for both sometimes.
