What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (2024)

You may be the lucky one and get one of those rare codes that only pop up once in a blue moon. The lack of available information only means that you have to go to a mechanic or a dealer to get the proper diagnosis. It happens from time to time.

This code stands for - Scr Line Heater #4 Circuit Failed Open and Scr Line Heater #4 Circuit Failed Open: Aftertreatment 1 Diesel Exhaust Fluid Line Heater 4 Current Below Normal Or Open Circuit; Open Load On Function "am_pwm_line_heating_4". Both sound more complicated than they really are.

To learn more about this fault code just continue to read our article. It will have the best information possible so you can make the best repair in a short amount of time. Getting everything back to normal is the goal of any repair.

SPN 4357 FMI 5

Diagnostic Code SPN 4357 FMI 5

If SPN 4356 FMI 5 is Set

Steps For SPN 4357 FMI 5 Repair

Diesel Exhaust Fluid Line Heater Resistance Chart

A Color-Coded Fault List

Diagnostic Code SPN 4357 FMI 5

What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (1)

When you see this code pop up on your screen do not be alarmed. From what we have been able to tell, there does not seem to be any performance issues or threat of derating.

According to the official SPN code list, this code represents an open circuit in your line heater. The repair will depend on what other codes are set at the same time.

The good news is that there should be only 6 steps to take if you do not resolve the problem sooner than that. There may only be 2 other fault codes that may be present when you attach your code reader.

Only two are mentioned in the data sheets. The first will be SPN 4355 FMI 5 and that code is telling you that you have an open circuit in Line heater #2. If you have these two codes, then the following work needs to be done:

repair open between pin 15 of the ACM2.1 120-pin connector

and pin 2 of line heaters 2 and 4.” That is all there is to it unless you only see SPN 4357 FMI 5. If that is the sole code, then you move on to the following 5 steps.

If SPN 4356 FMI 5 is Set

What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (2)

The other code that may appear with SPN 4357 FMI 5 is SPN 4356 FMI 5 and that code stands for - Scr Line Heater #3 Circuit Failed Open. The repair is going to be similar to the previous repair with one minor difference.

Instead of repairing heaters 2 & 4, you will be repairing the #2 pin of line heaters 3 & 4. You need to be careful as even these slight differences can cause some mistakes to be made.

Having two codes appear usually makes this repair easier as you only have one step. The more difficult repair will be when only the SPN 4357 FMI 5 code appears. Those steps are coming up.

Steps For SPN 4357 FMI 5 Repair

What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (3)

If you only have one code, then the first step to take would be to disconnect line heater #4. Then turn the key to the on position but leave the engine off.

The other steps are as follows:

4. Measure the voltage between pin 2 on the harness side of line heater 4 connectors and ground.

a. If the voltage is greater than 11.75, Go to step 5.

b. If the voltage is less than 11.75, repair the wire between pin 2 on the harness side of the line heater 4 connector and pin 15of the ACM2.1.

5. Measure the voltage between pin 1 on the harness side of the line heater 4 connector and ground.

a. If the voltage is between 2.25 and 2.50, Go to step 6.

b. If the voltage is not between 2.25 and 2.50, repair the wire between pin 1 on the harness side of the line heater 4 connectorand pin 32 of the ACM2.1.

6. Measure the resistance on the heating element side of the line heater 4. If resistance is not within this range, replace the line

heating element.” (source)

If you still see the code after completing those steps, double-check your work or go to an experienced mechanic to see if something else is wrong.

Diesel Exhaust Fluid Line Heater Resistance Chart

This table provides you with the proper resistance values.

Length in inches Nominal Resistance in ohms Minimum resistance in ohms Maximum resistance in ohms
19.6 16 12.8 19.2
39.3 9.8 7.84 11.76
47.2 8.6 6.88 10.32
55.1 7.8 6.24 9.36
62.9 7 5.6 8.4
70.8 6.1 4.88 7.32
78.7 5.6 4.48 6.72
86.6 5.2 4.16 6.24
94.4 4.9 3.92 5.88
102.3 4.6 3.68 5.52

The source from this table is the same link above. This is a simple repair that you should be able to do it yourself.

A Color-Coded Fault List

What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (4)

This may make your repair work even easier. The list we are about to link to is color coded with the legend at the top for easier understanding. There are 6 colors used to identify the exact type of problem you are experiencing.

These categories are- Yellow- Circuit Fault

Light blue- Rationality Fault

Red- Engine Protection Fault

Orange- Component Broadcasted Fault

Purple- Communication Data Fault

Light green- Information Fault

Knowing which type of problem you are facing helps you gather your tools faster and be ready for the type of repair you need to make. There are 24 pages of SPN FMI fault codes and on page 25 you will get a little more information to help you.

Just click here to get to this unique but very handy color-coded fault code list.

Some Final Words

It is possible that you may not see this code triggered any time soon or at all. It is not one that is talked about very often and the repair is fairly simple. There should be no impact on engine performance when you see this code but do not delay in getting it fixed. It could get worse if you ignore it.

What Is The Diagnostic Code SPN 4357 FMI 5? (Freightliner) (2024)

FAQs

What is the code FMI 5 on a Freightliner? ›

The FMI 5 in this example tells us that there is low current (amps) or an open in the circuit. Generally, this type of fault tells us that there is a wire that is broken or disconnected.

What is the diagnostic code SPN? ›

SPN is short for suspect parameter number. It identifies which electrical circuit, part or component of your truck isn't working properly. FMI stands for failure mode identifier—this part of the fault code tells you what type of problem your truck has.

What is code 54525 on Freightliner? ›

Most likely it thinks the DEF tank is empty because you have the 545 25 codes which is the sensor for the level valve in the tank itself. This will also cause you to have the issue wit hteh dpf system when that level sensor is faulting. Have that sensor tested and that level sensor changed out.

What is the code 790 on a Freightliner? ›

ABS code 790 is a ball detected with your wheel speed sensor right side axle 1 or front axle. Check the wiring harness and connector pins going to the wheel speed sensor and the wiring checks out okay with 100% certainty, replace the wheel speed sensor.

What does SPN and FMI mean? ›

These fields are: Suspect Parameter Number (SPN): Represents the SPN with error. Every defined SPN can be used in a DTC. Failure Mode Identifier (FMI): Represents the nature and type of error that occurred, e.g., value range violation (high or low), sensor short-circuits, incorrect update rate, calibration error.

What does FMI mean in diagnostics? ›

Failure Mode Identifier (FMI) Codes on J1939 data link. The FMI is used along with the SPN to provide specific information that relates to a diagnostic trouble code (DTC). The FMI may indicate that a problem with an electronic circuit or an electronic component has been detected.

How do I reset the SPN? ›

To reset the default SPN values, use the setspn -r hostname command at a command prompt, where hostname is the actual host name of the computer object that you want to update.

What does SPN mean in diagnostics? ›

SPN stands for Suspect Parameter Number. It's a diagnostic trouble code that provides detailed information about specific faults detected by the vehicle's ECU, making it easier to identify and address issues within the vehicle's electronic systems.

What does spn stand for? ›

Service Principal Name (SPN), used in the Kerberos protocol. Service provider name, stored on mobile phone subscriber identity module (SIM)

What is SPN 1077 code Freightliner? ›

SPN 1077/FMI 14 - GHG17

The Motor Control Module (MCM) monitors rail pressure during engine shut down and compares it to a stored learned value. If the bleed-down rate has changed due to leakage and it is below the learned value, this code will set.

What is ECM on Freightliner? ›

A truck Engine Control Module, or the ECM, is often times referred to as the engine's “brain”. The ECM is a computer that is attached to the side of the engine with functions such as receiving data from different sources on the truck (input) as well as reporting events or conditions (output).

What is Freightliner code SPN 563 FMI 14? ›

The SPN 563 FMI 14 fault code is originating in the ABS system. The SPN 807 FMI 9 ABS code is a short to ground on the modulator valve. it's mounted to the frame near the rear axles. Repair the ABS fault first and more than likely you will see the transmission code go away.

What is the code 5443 for Freightliner? ›

This fault is for high soot load in the DPF . Possible causes for this fault to come up are :-Low engine temperatures-Low engine load-Unnecessary excessive idle time . Step 1With a scan tool , connect and check for any other faults active along with this one .

What is SPN 103 code? ›

SPN 103/FMI 4

This fault Sets when the Motor Control Module (MCM) Detects a Short to Ground on the Turbocharger Speed Sensor Circuit.

What is the code SPN 677 FMI 5? ›

SPN 677/FMI 5

Description This fault sets when then MCM detects that there is an open on the Engine Starter Relay circuit.

What is the failure mode indicator FMI? ›

Failure Mode Indication (FMI), as part of the J1939 standard used in heavy-duty vehicles, functions by closely monitoring system components. When a fault occurs, FMI generates a precise code that identifies the specific nature of the issue, much like an advanced version of a 'check engine' light.

What does FMI mean Cummins? ›

FAILURE MODE IDENTIFIERS (FMI) Now that we have defined MID (The component) and PID (types of data), we can talk about Failure Mode Identifiers (FMI). Every diagnostic trouble code (DTC) that you find will have an FMI.

References

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