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SPN 99 — Oil Filter Differential Pressure

Do not driveMinutes

J1939 code SPN 99. Below — how the fault is worded at the factory by Ford Trucks, Renault Trucks and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.

Ford TrucksRenault TrucksZF AS-Tronic

Ford Trucks

Ford Trucks/Ecotorq writes fault numbers in its own format: the code in the table below is a Ford code (hexadecimal, zero-padded), not a J1939 SPN. It matches the standard only where the signal itself is standard, and usually matches the title of this page by digit alone.

FMI 0EMS Processor Internal Malfunction. FODP code (scan tool): P061B-63.
FMI 1EMS Module Internal Voltage – High. FODP code (scan tool): P0A10-00.
FMI 2EMS Module Internal Voltage – Low. FODP code (scan tool): P0A09-00.
FMI 3EMS Module Internal Main Relay – Early Opening. FODP code (scan tool): P1631-00.
FMI 4EMS Module Internal Main Relay – Stuck. FODP code (scan tool): P1631-68.
FMI 5EMS Processor Internal Malfunction. FODP code (scan tool): P0606-00.
FMI 6EMS Processor Internal Malfunction – Low Voltage. FODP code (scan tool): P0606-01.
FMI 7EMS Processor Internal Malfunction – High Voltage. FODP code (scan tool): P0606-02.
FMI 8EMS Processor Internal Malfunction. FODP code (scan tool): P0606-03.

Renault Trucks

FMI 8Transmission output speed sensor fault (Astronic sensor). Repair: Check the sensor. Check the wiring between the Astronic and the components (X1B/11). Switch the ignition off, switch it on again and repeat the test. If the fault persists, replace the control unit.

ZF AS-Tronic

ZF AS-Tronic uses its own fault numbering: the number in the table below is an internal ZF code, not a J1939 SPN. It matches the title of this page by digit only and means something different.

FMI 8No signal from the ZF "output shaft 1 speed" sensor.

What FMI means in J1939

SPN 99 FMI 099/0 · 99.0data above normal range (most severe level)
SPN 99 FMI 199/1 · 99.1data below normal range (most severe level)
SPN 99 FMI 299/2 · 99.2data erratic or intermittent
SPN 99 FMI 399/3 · 99.3voltage above normal or shorted high
SPN 99 FMI 499/4 · 99.4voltage below normal or shorted to ground
SPN 99 FMI 599/5 · 99.5current below normal or open circuit
SPN 99 FMI 699/6 · 99.6current above normal or grounded circuit
SPN 99 FMI 799/7 · 99.7mechanical system not responding
SPN 99 FMI 899/8 · 99.8abnormal frequency or pulse width

Can I keep driving

Do not drive. Stop as soon as it’s safe to do so — don’t keep going.

What happens if you keep driving

Time you have: Minutes

The oil film in the bearings is already breaking down. Every minute under load is metal on metal on the crank journals.

Next comes spun bearings and a full engine rebuild. Shut it down now and coast to the shoulder without revving.

The pressure itself is most likely fine: this is an electrical fault — an open or a short in the sensor circuit, not lost oil. You can drive, but the dash will no longer warn you about a real pressure drop. Until the circuit is repaired, check the level with the dipstick at every stop.

What to check on the spot

Shut the engine down. Check the oil level with the dipstick and look underneath for leaks. Don’t restart until pressure is back.

Nearby: lubrication

Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.