Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (2024)

Technology has created many codes. This is something you should come to expect when you buy an RV or a more modern truck or car. Because of technological advances over the decades, error codes are common. They tell you what is wrong and where the part may be located.

The SPN 3226 FMI error code has to do with the location or drift of the Nox outlet sensor. When this code comes up, it could be a dirty sensor or it has moved. The fix is to replace the sensor and it seems cleaning it is not an option.

To learn more about these codes, just continue to read our article. It explores the issue so you know what is wrong when you see the different codes pop up on your display. Take a few minutes to get familiar with these codes so you do not panic when you see them.

Code SPN 3226

Freightliner Code SPN 3226 FMI 20

SPN 3226 FMI 10

SPN 3228 FMI 2

SPN 3226 FMI 3

SPN 3226 FMI 4

SPN 3226 FMI 9

SPN 3226 FMI 13

SPN 3226 FMI 21

Freightliner Code SPN 3226 FMI 20

Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (1)

The funny thing about modern engines is that when a certain code comes up, the affected part will determine which company will fix the problem. For example, this error code tells everyone that if the Nox sensor is faulty then Cummins has to fix it.

If the wiring to the Nox sensor is faulty, then Freightliner has to fix it. It all depends on what part this code is referring to. It could be as reported above or that there is a problem with the wiring connecting the Nox Sensor to the vehicle’s ECM.

Once you get this code you know where to look and who to contact if you are still under warranty. If you are not under warranty, then you should be able to fix this problem yourself if you are mechanically inclined. It is up to you how you will get this problem fixed.

SPN 3226 FMI 10

The letters No in Nox mean nitrate oxide and the Nox sensor monitors this particular component in your vehicle. When you see an SPN 3226 FMI 10 error code then those numbers refer to- Abnormal Rate Of Change.

What that means is that the Nox Sensor is getting an invalid reading. The good news is that there is no effect on performance when you see this error code pop up.

The location of this sensor is usually in the exhaust system but that depends on the application it is being used for. In other words, it is not always located in the exhaust system.

According to one mechanic- “The aftertreatment outlet NOx (mono-nitrogen oxides) sensor is a smart device that communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment outlet NOx sensor performs its own internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually. The aftertreatment outlet NOx sensor is used to measure the NOx emissions at the outlet of the aftertreatreatment system”.

SPN 3228 FMI 2

Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (2)

For certain engines, the 3218 is not a valid error code and this may pop up at the same time you get the 3228 FMI 2 code. To clear that false code you may have to talk to a mechanic.

The SPN 3228 FMI 2 code should mean that the intake NOx sensor - data erratic, intermittent or incorrect has something wrong with it. If it is getting incorrect data.

When you see this code your truck may derate and it won’t get full power until you have the problem fixed. Fortunately, you may have some time before that derate takes place. You may be able to continue running at full power for 3 days before you have a performance issue.

Just take care of the problem as soon as you can so you do not get derated when you are in the middle of your day or travels.

SPN 3226 FMI 3

This code is telling one of two things or even both. First, it indicates there is trouble with the Scr Outlet Nox Sensor Circuit Failed High. Second, it could be a problem with Scr Outlet Nox Sensor Circuit Failed High: Aftertreatment 1 Outlet Nox Voltage Above Normal, Or Shorted To High Source; Nox Sensor (on Acm) Signal Range Failed High

What all that means is that there is trouble with the outlet NOx sensor and it should be replaced as soon as you can get the time. The nature of the problem can either be with the Nox sensor or with the wires attached to it.

If you are not trained to handle this type of repair, find a good mechanic who knows what to do and can get it done quickly for you. It should not affect performance right away but you can never tell with these new engines.

SPN 3226 FMI 4

Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (3)

The definition for this code is-- Aftertreatment Outlet NOx Sensor Circuit- Voltage below normal or shorted to low source"If this is a one=-off error code, then all you need to do is shut down your motor and turn it back on again. This should reset the code and remove the problem.

However, if this code keeps coming up after you tried that, then you should replace the sensor. Make sure to reset or clear the code after installing the new sensor.

That can be done by doing 3 successful starts. Also, make sure you change the right Nox sensor. There are two of them, an inlet and an outlet, and the wrong one gets changed all the time.

If you changed the wrong one, then the code will keep coming up til;l you change the right sensor. These two sensors are not interchangeable and have different part numbers.

What makes things worse is that they can plug into each other’s spot with ease.

SPN 3226 FMI 9

This code means- Aftertreatment 1 Outlet NOx Sensor - Abnormal update rate. o communications or invalid data transfer rate detected on the J1939 data link between ECM and the aftertreatment outlet NOx sensor SPN 3226 Fmi 9 Cnt 1

The source of the problem may be the sensor but it may also be the cab’s fuse box that got corroded in some manner. The fix is to replace the fuse box. If you own a Peterbilt truck, this is a known problem.

On other vehicles, it may not be the fuse box but check it just in case. In a Volvo, you will need to check the wiring first. Since the sensor is located in a vulnerable spot, it could have been hit by an object or got heated in some way.

Once you locate the sensor check the wires first and then the Nox sensor. Replace the latter and fix the wires to make sure this does not happen again.

SPN 3226 FMI 13

Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (4)

This code says something a little different and it means- "Aftertreatment 1 Outlet NOx Sensor - Out of Calibration". The fix is a bit different except that you will have to replace the sensor.

Also, you should reset the code and then run a forced regen for verification that the code has been cleared or reset. This step is for those round 9-pin diag connector and OBD 2-style diag port designs.

These are the steps to take even if you have not used your vehicle for a very long time. If you do not have the time to do those steps, unplug the speed sensor so you can go back to full speed till you get the Nox sensor fixed.

The speed sensor is at the back of the transmission and once pulled you will only get about 1500 RPMs. This trick only gives you about 200 miles of relief.

SPN 3226 FMI 21

This code translates into an Aftertreatment 1 Outlet NOx Sensor - Data not Rational - Drifted High. One mechanic has stated that the FMI numbers do not go that high, but we found it on the list of major Cummins error codes.

We have not found a mechanic that has talked about how to fix this problem but common sense says that it may mean the Nox sensor needs to be replaced. One thing we noticed was this error code is exactly the same as the SPN 3226 FMI 20 error code.

So the fix should be the same as explained at the beginning of this article. But if you are not sure, talk to a mechanic about it and see what they say.

Some Final Words

Getting your modern engine repaired can take some work. Not only do you have to know the error code language and what they mean, you still have to locate the failed part and either fix or replace it.

If you are not mechanically inclined, make sure you know an honest mechanic that can handle the problem for you. The key is to get these error codes fixed and cleared before your vehicle derates. Going 5 mph is not fun.

Freightliner: What Is Code SPN 3226 FMI 20, 10, 2, 4, 9? (2024)

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