John Deere Engines SPN3514FMI4 Fault Code: Sensor Supply #6 Voltage Out of Range Low
Also called Engine Shutdown Commanded by Application
Sensor Supply #6 Voltage Out of Range Low · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
SPN 3514 FMI 4 means the ECU has detected that Sensor Supply #6, a 5-volt supply circuit, has dropped below 4.6 volts. This supply feeds several engine sensors, and the ECU sets this code as a Warning while it tries to keep the affected systems running.
Medium severity. John Deere lists this as a Warning-level alarm, not an immediate shutdown code. The ECU keeps trying to maintain proper operating conditions, but because this supply feeds sensors tied to coolant pressure, exhaust filter monitoring, EGR, and DEF dosing, ignoring it can lead to inaccurate readings or reduced engine protection over time. Diagnose it within the shift rather than waiting.
What does John Deere Engines error code SPN3514FMI4 mean?
SPN 3514 FMI 4 points to a problem on the Sensor Supply #6 circuit, a shared 5-volt reference supply that the ECU sends out to power several sensors. This is not a code about one specific sensor failing on its own. It is about the supply voltage itself sagging below what the ECU needs to trust the readings coming back from any device on that circuit.
Depending on the engine and aftertreatment configuration, Sensor Supply #6 may power any combination of the Exhaust Filter Temperature Module, DPF Differential Pressure Sensor, Engine Coolant Pressure Sensor, Fuel Dosing Outlet Pressure Sensor, Fuel Dosing Inlet Sensor, Exhaust Manifold Pressure Sensor, or EGR Valve, depending on the specific engine and emissions system installed.
Because one supply circuit feeds multiple sensors, a single wiring fault, connector issue, or an overloaded circuit can knock out readings from several systems at once. John Deere flags this as a Warning alarm, meaning the ECU will try to keep things running while the underlying supply problem needs to be fixed.
What triggers a John Deere Engines SPN3514FMI4 code?
The ECU sets this code when it detects supply voltage on the Sensor Supply #6 circuit drop below 4.6 volts, and the code is displayed when the ignition is on and the fault is active.
Common causes of SPN3514FMI4
- A bad or failed sensor on the circuit: the Exhaust Filter Temperature Module, DPF Differential Pressure Sensor, Engine Coolant Pressure Sensor, Fuel Dosing Outlet Pressure Sensor, Fuel Dosing Inlet Sensor, Exhaust Manifold Pressure Sensor, or EGR Valve, depending on configuration.
- An open or short in the wiring harness between the ECU and the affected sensors, including a short to ground on the supply wire itself.
- Corroded, loose, or damaged terminals or connectors at the ECU.
- Corroded, loose, or damaged terminals or connectors at one of the sensors or the EGR valve listed above.
- Outdated or faulty ECU software.
- A failed ECU.
- Too many devices connected to this Sensor Supply circuit, causing the ECU to activate a current-limit shutdown because the load on the circuit is too great.
How to troubleshoot John Deere Engines SPN3514FMI4: first checks
- Before digging into wiring, confirm no aftermarket or added sensors, gauges, or accessories have been tapped into this Sensor Supply circuit. An overloaded supply will trip the ECU's current limit and mimic a wiring fault.
- Inspect the connectors and terminals at the ECU itself for corrosion, bent pins, or loose pins. A poor connection at the ECU end affects every sensor riding on that supply.
- Check the connectors at each sensor that uses Sensor Supply #6 for your engine configuration (coolant pressure sensor, DPF differential pressure sensor, exhaust filter temperature module, EGR valve, fuel dosing pressure sensors, or exhaust manifold pressure sensor) for corrosion, moisture intrusion, or damage.
- Trace the harness between the ECU and the affected sensors looking for chafed, pinched, or exposed wiring that could cause a short to ground or an open circuit.
- Verify ECU software is current, since outdated software is listed as a possible cause.
- If wiring and connectors check out clean, test each sensor on the circuit individually to isolate which one, if any, is pulling the supply voltage down or drawing excess current.
How the code clears
No separate clearing step is listed. Address the underlying cause (bad sensor, damaged harness, connector corrosion, overloaded circuit, or ECU issue) and the code should clear once the ECU sees Sensor Supply #6 voltage back within range. Cycle the ignition after repairs to confirm the fault does not return.
Frequently asked questions
What does SPN 3514 FMI 4 mean on a John Deere engine?
It means the ECU has detected that Sensor Supply #6, an internal 5-volt sensor supply circuit, has dropped below 4.6 volts. This supply feeds several sensors depending on your engine's configuration, so the code points to a supply problem rather than one specific failed part.
Is SPN 3514 FMI 4 a serious fault?
John Deere classifies it as a Warning-level alarm. The ECU tries to maintain proper operating conditions while the fault is active, so the engine typically keeps running, but the affected sensors may be giving unreliable readings until the supply issue is fixed.
Which sensors are affected by Sensor Supply #6?
Depending on the engine and emissions configuration, this circuit can feed the Exhaust Filter Temperature Module, DPF Differential Pressure Sensor, Engine Coolant Pressure Sensor, Fuel Dosing Outlet Pressure Sensor, Fuel Dosing Inlet Sensor, Exhaust Manifold Pressure Sensor, or the EGR Valve.
Can adding aftermarket accessories cause this code?
Yes. John Deere specifically warns that if too many devices are connected to this Sensor Supply circuit, the added load can trigger a current-limit shutdown on the supply, which will produce this same low-voltage fault.
What is the difference between SPN 3514 FMI 3 and FMI 4?
Both are part of the same troubleshooting sequence for the Sensor Supply #6 circuit. FMI 4 specifically covers the supply voltage being detected below the 4.6 volt threshold, while FMI 3 is listed as a related but separate fault in the same diagnostic path.
How do I fix SPN 3514 FMI 4?
Start by checking for overloaded wiring or added accessories on the circuit, then inspect connectors and terminals at the ECU and at each sensor on the Sensor Supply #6 circuit. From there check the harness for opens or shorts, verify ECU software is current, and test individual sensors if the wiring checks out.
Will this code clear on its own after I fix the problem?
No separate reset procedure is listed. Once the underlying wiring, connector, sensor, or software issue is corrected, the code should clear when the ECU sees the supply voltage return to normal. Cycling the ignition after the repair is a reasonable way to confirm the fix held.