What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (2024)

Once it is assigned a code, it seems that the definitions remain the same for a very long time. The trouble with engines having a set of fault codes, it may take you an hour to find the right one. They are not always listed in numerical order.

There are at least 6 different 3216 fault codes. They are given an FMI number to help distinguish each one from all the rest. The FMI 20 for this fault code means After treatment 1 Intake NOx Data Drifted High. It comes with a solid amber alert light.

To learn more about this code just continue to read our article. It explores the topic so you can have the right information at your fingertips. Take a few minutes to see how this information helps you diagnose the problem and come to the right solution.

Code SPN 3216

Diagnostic Code SPN 3216 FMI 18

Cummins Fault Code List

What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (1)

Because engines have become so complicated in recent decades, the makers of these diesel engines have developed a fault code system. This system is designed to provide you with the most information possible about a problem somewhere in your engine.

The problem with these fault code systems is that there are so many of them, that it can take about 15 minutes or more to find the one you are getting. Cummins has a list that is approx. 40 pages long.

That is a lot of fault codes to learn about. It would be better if you printed the list off and kept it somewhere safe so you can refer to it from time to time. If you click on this link, you will get to those 40 pages of codes.

The explanation for this code turns up on page 61 of the manual. The codes start on page 42 and stop at page 80 so you have a lot of potential issues you may encounter over the years you own the engine.

Print it out so you do not have to search for the codes again. Being prepared can save you a lot of time and money.

Cummins Fault Code SPN 3216 FMI 20

What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (2)

Keep in mind that the Cummins fault code will not be listed as the same numerals as the SPN FMI fault code. When you look at the fault code pages in the middle of the chart you will see the words fault code.

The number in that box is the Cummins fault code and for this particular one, the Cummins code is 3748. Here is what the code means-- 3216 /20 /Amber /Solid/

After treatment 1 Intake NOx Data Drifted High/ 3748/ After treatment 1 Intake NOx Sensor - Data not Rational - Drifted High/.

We left the 4 x’s off at the end of that row. If you do not understand engines or what that definition means then you need to talk to a diesel engine mechanic to get the full explanation as well as the parts or solution to the problem.

To keep up with the ever-changing motor industry, you may have to look up some websites that are very good at analyzing all the new information that is needed to work on a motor these days.

With all the regulations and new equipment needed on modern motors, the information required to fix a modern engine has grown substantially. This is not going to be your grandfather’s motor anymore.

Diagnostic Code SPN 3216 FMI 18

What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (3)

Unfortunately, the fault code we linked to did not seem to have room to include this fault code number. It skips from FMI 16 to FMI 20 but this error does not mean there is no SPN 3216 FMI 18 code.

All of the 3216 numbers refer to the inlet NOx sensor and we checked the list, the 7 codes listed there do relate to the NOx sensor. To get it running right and to remove the code, you may have to remove the part and put a new one in its place.

After that, you have to do a regen to tell the ECM to know that the NOx sensor is working like it should and reading properly. The code system may be confusing as there seem to be at least 31 3216 codes but only 7 are listed on that sheet we linked to.

That may throw some owners off. So if you get a 3216 code that is not listed you know it is referring to the NOx sensor. You would have to contact a good mechanic to get the rest of the information.

It is a hassle and we are long past the days when anyone and everyone could tell by the sound of the engine that something is wrong with it.

Cummins Fault Code List

What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (4)

If you need a more complete fault code list, you will have to do some searching on the internet or talk to Cummins directly. The list we are about to link to will help you with some of the codes but it is nowhere as complete as the previous list we linked to.

Why that is so, we do not know. But having more than one list on hand should help you track down the problem and get the repair done correctly. This list is compiled by Allied Systems and should be of some help to you.

Some Final Words

Modern engines are not the easiest to work on anymore. There are just too many parts and too many sources for problems. However, while the fault code lists you can find on the internet are helpful, they are often incomplete and only makes your problem more frustrating.

We suggest that you go to the dealer or approved repair shop to have those codes translated so you know exactly what needs to be done. Working on engines is not for the casual DIY mechanic anymore. There is a lot of education involved. You may not want to go back to school to work on your motor.

What Does Diagnostic Code SPN 3216 FMI 20 Mean? (Cummins) (2024)
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