John Deere Engines SPN 2630 FMI 3 Fault Code: Charge Air Cooler Outlet Temperature Signal Out Of Range High
Also called Charge Air Cooler Outlet Temperature Signal Out of Range High, Engine Shutdown Commanded by Application
Charge Air Cooler Outlet Temperature Signal Out Of Range High · ai-assisted, editor-reviewed · Last updated 2026-07-21
TL;DR
SPN 2630 FMI 3 means the ECU sees a charge air cooler outlet temperature signal voltage that is above the sensor's high voltage specification, which the ECU reads as a temperature colder than is physically possible. This is a Warning-level code. The ECU substitutes a default charge air cooler outlet temperature of -1° C (30° F) and tries to keep the engine running within its normal operating envelope while the fault is active.
Medium severity. This is logged as a Warning-level alarm, not an immediate shutdown code. The engine keeps running on a substituted default temperature value, but that default can mask real charge air temperature swings, so it should be diagnosed the same shift rather than ignored.
What does John Deere Engines error code SPN 2630 FMI 3 mean?
SPN 2630 FMI 3 is set when the charge air cooler outlet temperature sensor signal voltage climbs above the sensor's designed high voltage limit. Because this sensor's voltage-to-temperature relationship is inverse for this type of circuit, a voltage that high corresponds to a temperature colder than the engine could ever actually produce coming out of the charge air cooler, which is how the ECU knows the reading is invalid rather than a real cold reading.
When the code is active, the ECU stops trusting the live sensor signal and substitutes a fixed default charge air cooler outlet temperature of -1° C (30° F). It uses that default to keep trying to manage the engine's operating envelope, but any temperature-based adjustments the ECU would normally make based on real charge air temperature are no longer accurate.
The code sets whenever the ignition is on and the fault condition is active, so it will reappear at every key-on if the underlying wiring or sensor problem is still present.
Common causes of SPN 2630 FMI 3
- Bad terminals, pins, or connector at the charge air cooler outlet temperature sensor, including corrosion or a loose connection
- Bad charge air cooler outlet temperature sensor (internal short driving the signal voltage too high)
- Open or short in the harness wiring between the sensor and ECU, including high resistance, pinched, or melted wiring
- Bad terminals or connector at the ECU
- Bad ECU or bad ECU connector connection
- Intermittent connection in the harness that only shows the fault under certain conditions
- Bad or outdated ECU software
How to troubleshoot John Deere Engines SPN 2630 FMI 3: first checks
- Turn the ignition on and confirm the fault is currently active before starting, since this code is tied directly to key-on state.
- Inspect the charge air cooler outlet temperature sensor connector for corrosion, bent or backed-out pins, or a loose connection, since this is the first cause listed in every version of this diagnostic.
- Visually trace the harness between the sensor and the ECU looking for pinched, melted, or chafed wiring, especially anywhere the harness could rub against a hot or powered component, since a chafed signal wire shorting to a supply or reference voltage is a classic way to drive the signal voltage high.
- Check the ECU-side connector for corrosion or damaged terminals, and confirm the connector is fully seated.
- Wiggle-test the harness connectors while watching for the fault to change state, to catch an intermittent connection that only faults under vibration or movement.
- If wiring and connectors check out, test the sensor itself against its voltage specification, since a bad sensor is listed as a direct cause across all versions of this fault.
- Confirm the ECU software level is current, since outdated or bad ECU software is listed as a possible cause.
How the code clears
No separate clearing step is listed beyond repairing the underlying wiring, connector, sensor, or ECU software issue. Because the fault is evaluated continuously whenever the ignition is on, the code should stop setting on its own once the high-voltage condition is corrected. No reset procedure is listed for this code.
Frequently asked questions
What does SPN 2630 FMI 3 mean on a John Deere engine?
It means the ECU is seeing a charge air cooler outlet temperature sensor signal voltage that is above the sensor's high voltage specification, which corresponds to a temperature colder than is physically possible, so the ECU treats the reading as invalid.
Will SPN 2630 FMI 3 shut down my engine?
No. It is logged as a Warning-level alarm. The ECU substitutes a default charge air cooler outlet temperature of -1° C (30° F) and tries to keep the engine within its normal operating envelope rather than commanding a shutdown.
What is the difference between SPN 2630 FMI 3 and SPN 2630 FMI 4?
FMI 3 is the signal out of range high fault, caused by the signal voltage rising above the sensor's high specification. FMI 4 is the signal out of range low fault, a different electrical failure mode such as an open circuit or a signal shorted low, and it needs its own diagnosis focused on low-voltage causes rather than high-voltage causes.
How is SPN 2630 FMI 3 different from FMI 15 or FMI 16?
FMI 15 and FMI 16 describe the signal reading slightly high or moderately high, which are less severe deviations still within a plausible range. FMI 3 means the voltage is out of range high entirely, corresponding to a temperature that is not physically possible, which is why it triggers the ECU's default-value substitution rather than just a milder warning.
What causes the charge air cooler outlet temperature signal to read out of range high?
Listed causes include a bad connector or terminals at the sensor or ECU, a bad sensor, an open or short in the wiring harness including pinched or melted wiring, high resistance or intermittent connections in the harness, a bad ECU, or outdated ECU software.
Can I keep operating the machine with this code active?
The engine will keep running using the ECU's default temperature value, but because the ECU is no longer using the real charge air cooler outlet temperature to manage engine operation, the fault should be diagnosed and repaired promptly rather than run indefinitely.
Do I need to reset anything after fixing the wiring or sensor?
No separate clearing step is listed. The fault is checked continuously whenever the ignition is on, so once the wiring, connector, sensor, or software problem is corrected, the code should stop setting on its own.