John Deere Engines SPN412FMI4 Fault Code: EGR Temperature Signal Out Of Range Low
Also called EGR Temperature Signal Out of Range Low
EGR Temperature Signal Out Of Range Low · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
SPN 412 FMI 4 means the EGR (exhaust gas recirculation) exhaust temperature sensor signal voltage to the ECU has dropped below the sensor's low voltage specification, a value that corresponds to an EGR temperature that isn't physically possible. This is logged as a Warning-level fault, active whenever the ignition is on and the fault condition is present. The ECU will substitute a default EGR temperature value and try to keep the engine running within its normal operating envelope.
Medium severity. This is logged at Warning level, not a shutdown-level fault. The ECU compensates with a default EGR temperature value and keeps the engine running, but the EGR system may not be able to function correctly, so it should be diagnosed within the shift rather than ignored long-term.
What does John Deere Engines error code SPN412FMI4 mean?
SPN 412 FMI 4 points at the EGR exhaust temperature sensor circuit. The ECU monitors the voltage signal coming from this sensor to know how hot the recirculated exhaust gas is. When that voltage drops below the sensor's low voltage specification, the ECU interprets it as an impossible temperature reading, meaning the signal itself, not the actual exhaust gas, is out of range.
Because the reading is physically impossible, the ECU knows the sensor circuit itself has a problem rather than an actual temperature swing. It responds by using a default value for EGR temperature and trying to maintain the engine's normal operating envelope so performance and emissions control are not badly affected in the short term.
This code is closely related to SPN 412 FMI 3 (signal out of range, generally on the high or short-to-power side) but this page covers only FMI 4, the low-voltage/out-of-range-low condition.
Common causes of SPN412FMI4
- Bad terminals or connector at the EGR exhaust temperature sensor (corrosion, loose pins, or damaged connector body)
- Bad EGR exhaust temperature sensor (internal failure)
- Open or short in the wiring harness between the sensor and the ECU
- Pinched or melted wire in the harness
- Bad terminals or connector at the ECU
- Bad ECU
- Outdated or bad ECU software
How to troubleshoot John Deere Engines SPN412FMI4: first checks
- Turn the ignition on and confirm the fault is active, since this code is only displayed under that condition
- Inspect the EGR exhaust temperature sensor connector for corrosion, loose pins, or damage
- Trace the harness between the sensor and ECU looking for pinched, melted, chafed, or shorted wire
- Check the ECU connector and terminals for corrosion or poor contact
- Test the sensor itself against its low voltage specification to determine if it has failed internally
- Confirm the ECU software is up to date, since outdated software is listed as a possible cause
- If wiring and sensor check out, inspect ECU connections and consider ECU-level diagnosis
How the code clears
No separate clearing step is listed. Once the underlying wiring, connector, sensor, or ECU issue is repaired and the signal returns to a valid range, the fault should stop being active. Since it displays only while the fault condition is present and the ignition is on, verifying the repair typically means cycling the ignition and confirming the code no longer sets.
Frequently asked questions
What does SPN 412 FMI 4 mean on a John Deere engine?
It means the EGR exhaust temperature sensor's signal voltage to the ECU has dropped below the sensor's low voltage specification, which corresponds to a temperature that isn't physically possible. The ECU flags this as a Warning and substitutes a default EGR temperature value.
Is SPN 412 FMI 4 a serious fault?
It's logged at Warning level, not an immediate shutdown fault. The ECU keeps the engine running using a default EGR temperature value, but the EGR system's ability to function properly may be compromised, so it's worth diagnosing promptly rather than letting it run indefinitely.
What are the most common causes of this code?
The most frequently listed causes are bad terminals or connectors at the EGR temperature sensor or at the ECU, a bad EGR temperature sensor itself, and an open or short in the connecting harness. Pinched or melted wiring, a bad ECU, and outdated ECU software are also listed as possible causes.
Can I keep driving or operating with this code active?
The ECU will try to maintain the engine's normal operating envelope using a default EGR value, so the machine may continue to run. However, since this affects emissions and engine control systems, it should be diagnosed as soon as practical rather than left unaddressed.
How is SPN 412 FMI 4 different from FMI 3?
FMI 4 is the out-of-range-low condition, where the signal voltage drops below the sensor's low specification. FMI 3 covers a related out-of-range condition on the same sensor circuit. They share much of the same troubleshooting sequence and possible causes but are separate fault codes.
Do I need to reset the code after repair?
No separate clearing step is listed for this code. It is described as active only while the ignition is on and the fault condition is present, so once the wiring, connector, sensor, or ECU issue is properly repaired, the code should stop setting on its own.
What part of the truck or machine does this affect?
This code affects the EGR (exhaust gas recirculation) system's exhaust temperature sensor circuit, which is part of the engine's emissions control system. It does not directly affect steering, braking, or lifting functions.