John Deere Engines SPN 2630 FMI 15 Fault Code: Charge Air Cooler Outlet Temperature Signal Slightly High
Also called Engine Shutdown Commanded by Application
Charge Air Cooler Outlet Temperature Signal Slightly High · ai-assisted, editor-reviewed · Last updated 2026-07-21
TL;DR
SPN 2630 FMI 15 means the ECU sees the charge air cooler outlet temperature signal running slightly higher than expected once the engine has been running for at least 3 minutes. On some OEM engines this threshold is tied to 88° C (190° F). This is a Warning-level code, the ECU tries to keep the engine in normal operating parameters, and the engine does not shut down or derate for this specific fault.
Medium severity. This is logged as a Warning, not a Stop alarm. The ECU keeps trying to maintain normal operating conditions rather than derating power. Still, a slightly high charge air temperature signal can be an early sign of airflow, cooling, or sensor problems that get worse if ignored, so it should be diagnosed within the shift rather than parked indefinitely.
What does John Deere Engines error code SPN 2630 FMI 15 mean?
SPN 2630 refers to the charge air cooler outlet temperature sensor, which monitors the temperature of compressed intake air after it passes through the charge air cooler (intercooler) and before it enters the engine. This reading helps the ECU manage combustion temperatures, emissions, and turbo/EGR behavior.
FMI 15 means the signal is 'slightly high' compared to what the ECU expects for current operating conditions. This is a step below the more severe out-of-range-high or moderately-high variants. It usually points to a real but moderate rise in charge air temperature, or a sensor and wiring issue that is skewing the reading upward.
Because this is a Warning-level code, the ECU does not cut power or shut the engine down for this fault. It keeps controlling the engine within normal parameters, but the underlying airflow or cooling restriction, if left unaddressed, can push the system into the more serious FMI 3 (out of range high) or FMI 16 (moderately high) conditions.
What triggers a John Deere Engines SPN 2630 FMI 15 code?
The engine must be running for a minimum of 3 minutes before this DTC can become active. On OEM engines, one version of this diagnostic ties the fault to a charge air cooler outlet temperature reading of 88° C (190° F). The code sets when the signal reads slightly higher than expected for the operating conditions present at that time.
Common causes of SPN 2630 FMI 15
- Plugged or dirty air filter restricting intake airflow
- Charge air cooler with external or internal airflow obstructions, or internal plugging
- Loose fan belt or damaged fan shroud
- Major exhaust leak or boost leak
- EGR flow sensor venturi bracket loose
- Restricted exhaust system or high intake restriction
- Bad charge air cooler
- Bad turbo or VGT vanes sticking, or VGT vane position sensor incorrect
- Plugged EGR circuit or EGR system leak
- Bad terminals or connector at the charge air cooler outlet temperature sensor
- Open or short in the harness, including pinched or melted wires
- Bad charge air cooler outlet temperature sensor itself
- Defective engine housing, sensor housing, or O-ring at the sensor mounting point
- Bad or outdated ECU software
- Bad ECU or bad ECU connector connection
- Blockage on or near the radiator, malfunctioning cooling fan, bad radiator cap, or improper coolant level (cooling-system related causes listed in related diagnostic sequences)
- Excessively high ambient air temperature
How to troubleshoot John Deere Engines SPN 2630 FMI 15: first checks
- Let the engine cool if it has been under load, then inspect the air filter and intake system for plugging or restriction
- Visually inspect the charge air cooler (intercooler) core and end tanks for external debris, bent fins, or signs of internal blockage
- Check the fan belt tension and inspect the fan shroud for cracks or damage that would reduce airflow across the cooler
- Inspect the full length of the intake and exhaust tract for boost leaks, major exhaust leaks, or a restricted exhaust system
- Check the EGR flow sensor venturi bracket for looseness and inspect the EGR circuit for plugging or leaks
- Inspect the charge air cooler outlet temperature sensor connector and terminals for corrosion, looseness, or damage
- Trace the sensor harness for pinched, melted, chafed, or shorted wiring between the sensor and the ECU
- Confirm radiator condition: check coolant level, inspect the radiator cap, and look for blockage on or near the radiator core and hose leaks or cracks
- Check current ECU software level against the latest release and inspect the ECU connector for a solid connection
- With the engine running for at least 3 minutes, monitor the live charge air cooler outlet temperature reading against expected values for ambient conditions
How the code clears
No separate clearing step is listed for this code. Since it is a Warning-level fault, it should clear on its own once the actual charge air temperature returns to the expected range for the engine's operating conditions, or once the underlying airflow, cooling, or sensor/wiring fault is repaired. Cycling the key and running the engine past the 3 minute activation window is the practical way to confirm whether the condition has cleared.
Frequently asked questions
What does SPN 2630 FMI 15 mean on a John Deere engine?
It means the ECU's charge air cooler outlet temperature sensor signal reads slightly higher than expected for the current operating conditions, after the engine has run for at least 3 minutes. It is logged as a Warning, not a shutdown code.
Will this code shut my engine down or cause a derate?
No. For SPN 2630 FMI 15 specifically, the ECU continues to control the engine within normal operating parameters and tries to maintain proper conditions. It does not command a shutdown or derate for this fault.
What temperature triggers this code?
On some OEM engines, the charge air cooler outlet temperature threshold referenced is 88° C (190° F). The engine must also have been running for a minimum of 3 minutes before the code can set.
What is the most common real-world cause of this code?
Restricted airflow is the most frequent culprit: a plugged air filter, a dirty or obstructed charge air cooler, a loose fan belt, or a damaged fan shroud. Boost leaks, exhaust restrictions, and EGR system leaks are also commonly listed causes.
Could this just be a bad sensor or wiring instead of an actual overheat?
Yes. Bad terminals or connectors at the charge air cooler outlet temperature sensor, an open or short in the harness (including pinched or melted wires), a defective sensor housing or O-ring, or the sensor itself failing can all cause the signal to read slightly high even if actual airflow and cooling are fine.
How is SPN 2630 FMI 15 different from SPN 2630 FMI 16?
FMI 15 flags the signal as only slightly higher than expected, while FMI 16 (Moderately High) indicates a larger deviation from the expected reading. Both are on the same charge air cooler outlet temperature circuit, but FMI 16 represents a worse condition than FMI 15.
How does this differ from SPN 2630 FMI 3 or FMI 4?
FMI 3 (Out Of Range High) and FMI 4 (Out Of Range Low) indicate the signal has moved completely outside the plausible voltage or value range, which usually points more directly at a wiring or sensor circuit failure. FMI 15 is a subtler deviation where the signal is still in range but running warmer than expected for the conditions.