John Deere Engines SPN102FMI4 Fault Code: Manifold Air Pressure Signal Out of Range Low
Also called Manifold Air Pressure Input Voltage Low, Manifold Air Pressure Signal out of Range Low
Manifold Air Pressure Signal Out of Range Low · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
SPN 102 FMI 4 means the ECU sees a manifold air pressure (MAP) sensor input voltage below 0.3 volts, a level that corresponds to a pressure lower than what is physically possible in the intake manifold. The ECU falls back to a default MAP value (some applications cite 200 kPa / 29 psi / 2.0 bar) and, depending on the control unit response listed, may derate the engine or eventually stop it.
High severity. Some versions of this fault list an alarm level of Warning with the ECU running on a default MAP value, while another version lists an alarm level of Stop with engine derate, EGR valve fully closed, and an automatic engine shutdown after 15 minutes of continuous active fault. Because the more severe response is possible, treat this as a high-priority fault until you know which behavior your machine's software applies.
What does John Deere Engines error code SPN102FMI4 mean?
The MAP sensor is a pressure transducer mounted to sense intake manifold air pressure. It sends a voltage signal to the ECU that rises as manifold pressure rises and falls as manifold pressure falls. The ECU combines this signal with the manifold air temperature (MAT) sensor input to calculate how much air is entering the engine, which affects fueling, boost-related calculations, and in some applications EGR and engine protection logic.
SPN 102 FMI 4 sets when that voltage drops below the sensor's low voltage specification, a level that represents a manifold pressure lower than what is physically possible. In other words, the ECU knows the signal cannot be real and treats it as a wiring or sensor fault rather than an actual low-pressure condition.
Once the fault is active, the ECU substitutes a default 'limp-home' MAP value so the engine keeps running, but the engine is no longer getting a real air pressure reading. Depending on the specific control module and software, this can trigger engine protection actions ranging from a simple warning to a full derate and shutdown.
What triggers a John Deere Engines SPN102FMI4 code?
The code sets when manifold air pressure input voltage drops below the sensor's low voltage specification, listed as 0.3 volts for OEM engine applications. This voltage corresponds to a manifold pressure lower than what is physically possible, which is how the ECU distinguishes a wiring or sensor fault from a real pressure reading. The fault is displayed when the ignition is on and the fault is active, and in at least one version specifically when the ignition is on, the engine is running, and the fault is active.
Common causes of SPN102FMI4
- Bad terminals or connector at the manifold air pressure sensor, including dirty, damaged, or poorly positioned pins
- Bad terminals, pins, or connector at the ECU connector (some listings reference the 60-way ECU connector)
- Open or short in the wiring harness between the sensor and the ECU, including a mispinned connector
- Open or high resistance in the sensor's return or supply wiring circuit
- Bad manifold air pressure sensor (or manifold air and exhaust pressure sensor on applicable engines)
- Bad ECU software
- Bad ECU
How to troubleshoot John Deere Engines SPN102FMI4: first checks
- Without disconnecting anything first, visually inspect the ECU connector and the MAP sensor connector for contamination, corrosion, damage, or terminals that are pushed back or poorly seated
- Inspect the wiring harness between the MAP sensor and the ECU for chafing, pinches, or exposed conductors that could cause a short or open circuit
- Check for a Sensor Supply Voltage Low DTC first. If one is active, troubleshoot that fault before chasing SPN 102 FMI 4, since a low supply voltage can cause this code as a downstream effect
- Confirm the sensor connector and any inline connectors are fully seated and locked, then recheck for the fault after the ignition cycle
- If wiring and connectors check out, test the MAP sensor's signal, supply, and return circuits with the sensor connected and disconnected to isolate a bad sensor from a bad harness or ECU
How the code clears
No separate clearing procedure is listed for this code beyond correcting the wiring, connector, sensor, or ECU issue. Once the underlying open, short, or grounded circuit is repaired, or the sensor or ECU is replaced as needed, the fault should stop being active on the next ignition cycle. If the alarm level for your application is Stop, be aware the ECU may have already commanded an engine stop after 15 minutes of continuous active fault, so a repair should be made before returning to full duty.
Frequently asked questions
What does SPN 102 FMI 4 mean on a John Deere engine?
It means the ECU detected the manifold air pressure (MAP) sensor signal voltage below 0.3 volts, a level lower than what is physically possible for real intake manifold pressure. The ECU treats this as a wiring, connector, sensor, or ECU fault rather than an actual pressure reading.
Will SPN 102 FMI 4 shut my engine down?
It depends on which control unit response applies to your machine. Some versions only issue a Warning and keep the engine running on a default MAP value. Other versions carry a Stop alarm level, derate the engine, command the EGR valve fully closed, and will command an engine stop after 15 minutes of continuous active fault.
Can I keep driving or working with this code active?
If the alarm level is Warning, the engine keeps running on a default MAP value, but you should still get it diagnosed soon since air flow calculations are no longer based on a real reading. If the alarm level is Stop with derate active, treat it as a shutdown risk and get the machine to a safe stopping point before it powers down on its own.
What should I check first for this code?
Start with a visual inspection of the MAP sensor connector and the ECU connector without disconnecting them, looking for corrosion, damage, or poor terminal positioning. Also check for an active Sensor Supply Voltage Low code, since that should be fixed first if present.
What are the most common causes of SPN 102 FMI 4?
Bad terminals or connectors at the MAP sensor or ECU, an open or short in the harness between them, a bad MAP sensor itself, bad ECU software, or a bad ECU. High resistance in the sensor's return or supply wiring is also listed as a cause.
Is the MAP sensor the same as the manifold air and exhaust pressure sensor?
On some engines the sensor is described specifically as a manifold air and exhaust pressure sensor rather than a standalone MAP sensor. The fault logic and low voltage condition are the same, so treat the diagnostic approach the same way regardless of which sensor name applies to your engine.
Does this code affect other systems like the EGR?
On applications with the Stop alarm level, yes: the ECU commands the EGR valve fully closed in addition to deratring the engine. On Warning-level applications, no EGR action is listed.