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SPN 100 is the oil-pressure signal; the FMI beside it says whether the reading is low, high or a sensor fault. This page covers LOW pressure (FMI 1, 17, 18): oil pressure has dropped below the minimum safe operating threshold. Low oil pressure can cause severe engine damage within minutes as bearings, pistons, and camshafts rely on pressurized oil for lubrication and cooling. This fault requires immediate engine shutdown to prevent catastrophic failure.
SPN-100 reports engine oil pressure. The FMI (Failure Mode Identifier) shown beside it says how the reading is wrong. FMI meanings follow the SAE J1939 standard used by Cummins and most modern diesel engine controllers.
SPN-100 FMI 0
Oil pressure far above normal — usually a cold start, a stuck relief valve or a faulty sender, not a low-oil emergency.
Check first: Confirm with a mechanical gauge when warm; check the relief valve and the sender.
SPN-100 FMI 1
Oil pressure far below normal (most severe). Most controllers treat this as a shutdown.
Check first: Stop the engine. Check the oil level, then confirm the real pressure with a mechanical gauge before any restart.
SPN-100 FMI 18
Oil pressure below normal (moderately severe).
Check first: Oil level and grade, oil filter, and a mechanical gauge reading at idle and at rated speed.
SPN-100 FMI 17
Oil pressure slightly below normal (least severe) — an early warning.
Check first: Oil level, filter condition and whether the last oil change used the correct viscosity.
SPN-100 FMI 2
The pressure signal is erratic or does not make sense.
Check first: Sensor connector, harness chafing and the sensor ground.
SPN-100 FMI 3
Sensor signal voltage above normal — usually an open circuit or a short to the supply.
Check first: Open signal or return wire, corroded connector pins, the 5 V sensor supply.
SPN-100 FMI 4
Sensor signal voltage below normal — usually a short to ground.
Check first: A chafed wire touching the engine or chassis, or a failed sensor.
FMI 2, 3 and 4 point at the sensor circuit rather than the oil system. Confirm the actual pressure with a mechanical gauge before replacing parts.
Need parts? Call us with your engine or controller model and we will confirm what we can supply and when.Call +254 768 860 665
Absolutely not. Running an engine with low oil pressure will cause rapid bearing wear and can destroy the engine within minutes. Stop immediately and diagnose the cause.
If oil level is correct but pressure is low, the oil pressure sensor may be faulty. Verify with a mechanical gauge. If actual pressure is low, the oil pump or bearings may be worn.
Send us the code or alarm and what the generator is doing, and one of our engineers will help you diagnose it.
Search other controller alarms and engine fault codes, with troubleshooting steps, in Generator Oracle.
Launch Generator Oracle →Full diagnostic guide
A fault code names a symptom, not a cause. Our engineers have written the diagnostic sequence they use on site for this class of fault — ranked causes, ordered steps with the reading expected at each one, and the point at which to stop and call someone.
9 diagnostic steps · intermediate · technician
8 diagnostic steps · advanced · technician