John Deere Engines SPN412FMI15 Fault Code: EGR Temperature Signal Slightly High
EGR Temperature Signal Slightly High · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
SPN 412 FMI 15 means the ECU sees the EGR temperature signal reading slightly higher than expected for current operating conditions, or in some ECU software versions, an EGR temperature of 280° C (536° F). The engine must run for at least 3 minutes before this code can set. Alarm level is Warning, and the ECU will derate engine power up to 5 percent.
Medium severity. This is a Warning-level code, not a Stop alarm. The engine keeps running but power is derated up to 5 percent while the ECU tries to protect the EGR and cooling system. Left unaddressed, an actual high EGR temperature can point to cooling or exhaust restriction problems that get worse over time.
What does John Deere Engines error code SPN412FMI15 mean?
SPN 412 FMI 15 is set on John Deere engines when the ECU's EGR (Exhaust Gas Recirculation) temperature signal reads slightly higher than what is expected for the operating conditions present when the code sets. The EGR system recirculates a portion of exhaust gas back into the intake to lower combustion temperatures and reduce emissions, so the ECU watches this temperature closely to keep the system working correctly and to protect EGR components from heat damage.
On many OEM engine applications, this code corresponds to the ECU sensing an EGR temperature around 280° C (536° F). The code requires the engine to be running for at least 3 minutes before it can go active, which filters out normal warm-up temperature swings.
Because the alarm level is Warning rather than Stop, the ECU responds by deratting maximum engine power up to 5 percent while trying to maintain proper operating conditions. This is the engine's way of protecting itself while still letting you get the machine to a safe stopping point or back to the shop.
What triggers a John Deere Engines SPN412FMI15 code?
The DTC becomes active when the engine has been running for a minimum of 3 minutes and the EGR temperature signal is reading slightly higher than expected for the operating conditions, or in some ECU software configurations, when the sensed EGR temperature reaches 280° C (536° F). On engines using that specific threshold, code SPN 1569 FMI 31 (referenced in related documentation as 001569.31) is also set when SPN 412 FMI 15 is active.
Common causes of SPN412FMI15
- Loose fan belt, which reduces cooling fan speed and airflow across the radiator
- Damaged fan shroud, which lets air bypass the radiator instead of pulling through it
- EGR flow sensor venturi bracket loose
- Low coolant level or leaks and cracks in the cooling system, including radiator hoses
- Bad or outdated terminals, connectors, or wiring (open or shorted harness) at the EGR temperature sensor or at the ECU
- Bad EGR temperature sensor, sensor housing, or O-ring defects
- Plugged, restricted, or leaking EGR circuit, including a restricted or blocked EGR cooler
- Bad EGR cooler or bad EGR valve
- VGT (variable geometry turbocharger) vanes sticking, or a VGT vane position sensor reading inaccurately
- Damaged turbocharger
- Intake or exhaust restrictions, exhaust leaks, or other signs of high exhaust temperature in the exhaust system
- Blockage on or near the radiator, malfunctioning cooling fan, or bad radiator cap
- Excessively high ambient air temperature
- Bad ECU software (outdated) or a bad ECU itself
How to troubleshoot John Deere Engines SPN412FMI15: first checks
- Check the cooling system first: verify coolant level is correct, inspect for leaks or cracked hoses, check the fan belt tension, inspect the fan shroud for damage, and confirm the cooling fan and radiator cap are working properly
- Look for anything restricting airflow to the radiator or restricting the charge air cooler, and check for excessively high ambient temperature conditions that could explain the reading
- Inspect the EGR temperature sensor connector and terminals for corrosion, looseness, or damage, and inspect the sensor housing and O-ring for defects
- Trace the wiring harness between the EGR temperature sensor and the ECU for opens or shorts
- Inspect the EGR valve, EGR cooler, and EGR flow sensor venturi and its bracket for looseness, restriction, or leaks
- Check the exhaust system for leaks, restrictions, or other signs consistent with abnormally high exhaust temperature
- Inspect the turbocharger and VGT vanes for sticking, and check the VGT vane position sensor reading for accuracy
- Verify ECU software is current, and check ECU connector terminals for good connection before considering ECU replacement
How the code clears
No separate clearing step is listed beyond fixing the underlying cause. Once the fault condition is corrected, such as restoring proper coolant level, repairing a wiring or connector issue, or replacing a bad sensor, the code should stop being active on subsequent engine run cycles. If a related code such as SPN 1569 FMI 31 was also set, that should be checked and cleared as part of the same repair.
Frequently asked questions
What does SPN 412 FMI 15 mean on a John Deere engine?
It means the ECU's EGR temperature signal is reading slightly higher than expected for the current operating conditions, or on engines using a fixed threshold, the sensed EGR temperature reached 280° C (536° F). The engine must have been running for at least 3 minutes for the code to become active.
Is SPN 412 FMI 15 a serious problem?
It is set at Warning alarm level, not Stop, so the engine keeps running. However, the ECU will derate maximum engine power up to 5 percent while the fault is active, and the underlying cause, such as a cooling system leak or EGR restriction, can lead to bigger problems if ignored.
Why does John Deere derate engine power for this code?
The derate, up to 5 percent, is the ECU trying to protect the EGR system and engine from an EGR temperature reading that is higher than it should be for the conditions, while still keeping the machine operable.
Can a loose fan belt actually cause this code?
Yes, a loose fan belt reduces cooling fan performance and airflow through the radiator, which can raise EGR and coolant temperatures enough to trigger this fault. It is one of the first and easiest things to check.
Does low coolant level trigger SPN 412 FMI 15?
Low coolant level is listed as a possible cause. Reduced coolant volume affects the engine's ability to manage heat, which can push EGR temperature readings above the expected range.
What is the relationship between SPN 412 FMI 15 and SPN 1569 FMI 31?
On engines that use the 280° C (536° F) EGR temperature threshold, SPN 1569 FMI 31 (also referenced as 001569.31) is set at the same time SPN 412 FMI 15 becomes active.
How long does the engine need to run before this code can set?
The engine has to run for a minimum of 3 minutes before the ECU will consider setting SPN 412 FMI 15, which avoids false triggers during normal cold start warm-up.