John Deere Engines SPN100FMI4 Fault Code: Engine Oil Pressure Signal Out of Range Low
Also called Engine Oil Pressure Input Voltage Low, Engine Oil Pressure Signal out of Range Low
Engine Oil Pressure Signal Out of Range Low · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
SPN 100 FMI 4 means the ECU sees an oil pressure input voltage that is impossibly low, below 0.1 volts on some systems or below a sensor's low voltage specification such as 0.3 volts on others, or the oil pressure switch is closed with the key on and no engine running. When this sets, the ECU disables its low oil pressure engine protection feature and runs on a default oil pressure value instead of the real reading.
High severity. This code does not stop the engine by itself, but it disables the ECU's low oil pressure protection feature. That means if you actually develop a real low oil pressure condition while this fault is active, the engine has no automatic protection and can suffer bearing or internal damage before anyone notices. Diagnose before extended operation.
What does John Deere Engines error code SPN100FMI4 mean?
SPN 100 FMI 4 is set by the engine ECU when the oil pressure signal it receives is electrically impossible, not just low. On sensor-equipped engines, the oil pressure sensor is a pressure transducer on the main oil gallery (or oil cooler on some systems) that produces higher voltage as oil pressure increases. If that voltage drops below 0.1 volts (or below the sensor's low voltage specification, which is 0.3 volts on OEM applications), the ECU knows this is not a real pressure reading, it is a wiring or sensor fault.
On switch-equipped engines, the oil pressure switch is normally open while the engine runs with adequate pressure and closes only when pressure drops below the minimum threshold. If the switch is closed with the key on and the engine not turning, that is also not physically valid, so the code sets.
Once the fault sets, the ECU can no longer trust the oil pressure signal. On sensor systems it substitutes a default oil pressure value (reported as 260 kPa (2.6 bar) (37.5 psi) in some manuals, 500 kPa (5.0 bar) (72.5 psi) in others depending on the application) and disables the low oil pressure protection feature entirely. On switch systems, the vehicle displays a warning fault light, which may be a blinking warning light depending on the application.
What triggers a John Deere Engines SPN100FMI4 code?
For sensor-equipped engines: oil pressure input voltage drops below 0.1 volts, or below the sensor's low voltage specification of 0.3 volts on OEM applications (other applications use a different spec found in that engine's application specifications). For switch-equipped engines: the oil pressure switch is closed while the key is on and engine speed is zero.
Common causes of SPN100FMI4
- Bad or corroded terminals or connector at the oil pressure sensor (or switch)
- Bad or corroded terminals or connector at the ECU, including the ECU's 30-way connector
- Open circuit in the oil pressure input wiring between the sensor and ECU
- Short to ground in the oil pressure input circuit
- Open circuit in the oil pressure sensor's 5 volt supply circuit
- Short to ground in the oil pressure sensor's 5 volt supply circuit
- Faulty oil pressure sensor or switch itself
- Faulty ECU
How to troubleshoot John Deere Engines SPN100FMI4: first checks
- Before disconnecting anything, visually inspect the ECU connectors and oil pressure sensor connector for contamination, corrosion, damage, or a connector that is not fully seated
- If a Sensor Supply Voltage Low DTC is also active, troubleshoot that fault first since a low 5 volt supply will cause this code as a side effect
- Check the wiring harness between the sensor and ECU for chafing, pinches, or damage that could cause an open or a short to ground
- Use a connector adapter test kit (John Deere JT07328) to probe connector terminals rather than forcing probes directly into the connector, to avoid terminal damage
- Confirm engine oil level and general condition are normal so you are not chasing a wiring fault when there is also a genuine mechanical oil pressure problem
- Verify actual oil pressure with a mechanical gauge if available, since the ECU is running on a default value and cannot warn you of a real low pressure condition while this code is active
How the code clears
No separate reset procedure is listed for this code. Once the underlying wiring, connector, sensor, or switch fault is repaired and the input voltage returns to a valid range, the code should clear on its own after a key cycle or short run. Always recheck with a scan tool that the fault is no longer active and that low oil pressure engine protection has been restored.
Frequently asked questions
What does SPN 100 FMI 4 mean on a John Deere engine?
It means the ECU's engine oil pressure signal is reading impossibly low, either the sensor voltage is below its minimum valid range or the oil pressure switch is closed when the engine is not turning. It points to a wiring, connector, sensor, or switch problem rather than necessarily a real oil pressure problem.
Is it safe to keep running the engine with this code active?
It is risky. The ECU disables its low oil pressure engine protection feature when this code is set, so if you develop a genuine low oil pressure condition while the code is active, the engine will not get the automatic protection it normally would. Diagnose and repair as soon as possible.
Does the engine lose oil pressure when this code sets?
Not necessarily. The ECU is not reporting your real oil pressure once this code is active, it substitutes a default value such as 260 kPa (2.6 bar) (37.5 psi) or 500 kPa (5.0 bar) (72.5 psi) depending on the application. The actual physical oil pressure could be fine or could be a real problem, you cannot tell from the dash alone.
What is the most common cause of SPN 100 FMI 4?
Connector and wiring issues at the oil pressure sensor or the ECU are common causes, including corroded or damaged terminals, an open or shorted signal circuit, or a fault in the sensor's 5 volt supply circuit. A failed sensor or switch, or a faulty ECU, are also possible causes.
What voltage triggers this fault code?
On some engines the code sets when input voltage drops below 0.1 volts. On other applications with a different sensor specification, it sets below 0.3 volts, which is the low voltage specification listed for OEM applications. Check the application specifications for your specific engine if these don't match.
Can I safely probe the connector to test for this fault?
Do not force test probes into the connector terminals, this can damage them. John Deere specifies using a connector adapter test kit (JT07328) to make measurements without damaging the terminals.
Will fixing the wiring clear the code by itself?
No separate reset procedure is documented. Once the electrical fault is repaired and the input voltage is back in a valid range, the code should clear on its own, but confirm with a scan tool that it is gone and that oil pressure protection is active again.