What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (2024)

All it states on the official FMI code lists is ‘condition exists’. You may already know that because your vehicle is not operating as it should. It could be more helpful if it provided a source and not more frustration.

The code SPN 3362 is supposed to be for- the Diesel Emission Fluid system. If you go to a non-Cummins or Spartan repair shop, you may not get the service you need.

To learn more about this fault code just continue to read our article. It combs the topic to provide the best information possible so you do not have to wait 3 to 4 months to get your RV back from the shop. That is the time frame for one Non-Cummins repair shop.

What is Trouble Code SPN 3362?

This code may not be on the official SPN code list but it is on the complete Cummins fault code list. Its Cummins equivalent is 1682 and it stands for - Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Input Lines.

The description that comes after this fault code explanation is- Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Input Lines - Condition Exists- This is not much help either.

There is more good news though, there are 11 steps you can take to fix this problem. Unlike the poor owner who got towed to the wrong repair shop. Those mechanics have spent 3 weeks working on his fault code and have not solved the problem.

The bad news is that while we can list the 11 steps, there are 15 more pages with repair instructions to follow. You can read those instructions at this link. The 11 steps you may have to take:

1 Check for primary fault codes

2 Aftertreatment diesel exhaust fluid dosing unit line or fittings are cracked,plugged or restricted

3 Aftertreatment diesel exhaust fluid is contaminated

4 Aftertreatment diesel exhaust fluid dosing valve pressure sensor ismalfunctioning

4.1 Aftertreatment diesel exhaust fluid pressure sensor open circuit check

5 Aftertreatment diesel exhaust fluid dosing valve pressure check

5.1 Aftertreatment diesel exhaust fluid dosing valve return restriction check

6 Aftertreatment Diesel Exhaust Fluid Voltage Drop Test

7 Aftertreatment diesel exhaust fluid dosing unit suction test

7.1 Aftertreatment diesel exhaust fluid dosing unit return circuit check

7.2 Aftertreatment diesel exhaust fluid dosing system cleaning

8 Aftertreatment diesel exhaust fluid dosing unit intake restriction

9 Aftertreatment diesel exhaust fluid pressure line restricted

9.1 Aftertreatment diesel exhaust fluid dosing unit is malfunctioning

10 Aftertreatment Diesel Exhaust Fluid Doser Pump Override test

11 ECM calibration revision history check

Cummins SPN 3362 FMI 31

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (1)

We have given you the explanation and description for this fault code already. And we have also given you the 11 steps you need to take to fix this problem. There are too many pages to read through to effectively post them here but you will find them at that link above.

However, there is an important piece of information that you should know about before you go to that link. There is a list of other codes that may be set along with this one.

To find those codes, you have to attach the Cummins-approved diagnostic code reader or electronic service tool to start your work. There is a long list of additional codes you should keep your eye out for:

Before troubleshooting this fault code, troubleshoot any fault code that is active or has more than one inactive countwithin the last 25 engine operating hours from the following list:

- Aftertreatment diesel exhaust fluid system: 1671, 1673, 1683, 1684, 1712, 1713, 3237, 3239, 3242, 3422, 3497,

3498, 3562, 3563, 3567, 3568, 3571, 3572, 3575, 3596, 5278, 5867, 5935

-Aftertreatment diesel exhaust fluid dosing unit: 3558, 3559”

As you go through the subsequent pages in that repair link, you will see the steps you need to take to make the repair as well as to do the validation. It will take some time to clear this code and repair it.

Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Input Lines

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (2)

There are a lot of complicated explanations concerning this area of your aftertreatment system. The key words would be ‘dosing’ and ‘input’ as that gives you the exact information you need to know.

These lines being in the DEF fluid so that can be sprayed in a light mist over the exhaust fumes and reduce the nitrogen that is released into the air. The problem these lines may not be bad at all. At worse, they may be kinked, or there is a leak somewhere in the lines.

The actual problem may be with the pump that delivers the fuel to the lines. If it fails, then there is no dosing of the exhaust fumes. What makes these explanations complicated is that they do not talk about the input dosing lines. Even the following diagram from Cummins does not list them in their legend:

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (3)

** diagram and legend are from this link- https://www.cummins.com/components/aftertreatment/how-it-works

The Legend:

1 - Engine 2 - ECM 3 - Charge Air Cooler 4 - EGR Cooler

5 - Turbocharger 6 - Engine Out NOx Sensor 7 - EGR Valve

8 - Temperature Sensors (4) 9 - DPF Sensor Table

10 - UL2 Dosing Module 11 - Compact Mixer Sensor Table

12 - UL2 Supply Module 13 - NOx Sensor 14 - PM Sensor

15 - DEF Tank 16 - SCR Catalyst 17 - DPF 18 - DOC

As the web page explains, this system is designed to make sure all emissions coming from your vehicle meet current emissions regulations. It just may be a complicated and expensive repair. Especially if you do not get towed to an approved Cummins or Spartan repair facility.

SPN 3362 FMI 14 Caterpillar

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (4)

As we have said, it is not always easy to find all the fault codes that can be set on your dash fault code system. We have checked several lists for CAT and one list simply copies what the official SPN fault code list does.

It leaps from 3361 to 3363 without any word for 3362. Most likely, the CAt side of this code will also deal with the DEF system. FMI 14 on another CAT fault code list states- “″Special Instruction”. FMI 14 is used when a special procedure or more detailed information is required to understand it.”

What this information is probably telling you is that you need to go to a mechanic who has a dealer-level fault code diagnostic tool to get to the bottom of this problem. We have not found any independent repair information for this code for CAT other than what has been linked above.

This is a generic reply that may or may not apply to your CAT engine- “Either you have too low DEF, bad DEF, or the injector for the DEF needs to be cleaned. Most times the dealer will perform a manual regen on the truck and this will solve the problem.” (source).

That is as close as we have been able to come up with this code. Talk to your CAT dealer or mechanic and see what they say. The engine may still be under warranty and you can get it fixed for very little out of pocket money.

SPN 3362 FMI 7

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (5)

Unfortunately, only 3362 FMI 31 shows up on the complete Cummins Fault code list. There may be a very good reason for this. We did find many 3362, 3363, & 3364 codes on that list and they all seem to point to the DEF system.

We have learned in our research that while there are different codes, the repair steps are very similar. What we are going to suggest is that you talk to your mechanic or dealer about this situation.

It may be that the other close codes may identify the problem for any SPN 3362 code other than FMI 31. In our research, no one is talking about this code or how to repair it.

Any information popping up is for 3362 FMI 31 only. This is a common problem as not everyone needs to go to any online website and discuss the 3362 codes. With Cummins' list pointing to the same type of problem, there may be no need to do that.

Some Final Words

Fault code lists are not perfect. You may have gathered that by reading all of our articles on these fault codes. Some have a lot of information and others do not.

In this case, this code is for the DEF system which already has a long list of codes that refer to the same or similar problems. The best thing to do when you see this code is to get to your mechanic as quickly as possible as you may get derated very quickly.

What Is Fault Code SPN 3362 FMI 31? (Cummins Aftertreatment) (2024)
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