SPN 107 — Air filter differential pressure
Safe to driveEnough to reach the yard
Updated: 2026-11-14
J1939 code SPN 107. Below — how the fault is worded at the factory by KAMAZ-5490, Mercedes-Benz, Renault Trucks and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.
Detailed breakdown
How to check it yourself
The air filter clogging sensor: it measures the pressure drop across the filter. The more the filter is clogged, the greater the drop, and the more the unit restricts the air supply.
What it should read
| Pressure drop across a clean filter | minimal — per the manufacturer's manual |
| Drop limit at which the filter is changed | per the manufacturer's manual |
Check order
- Inspect the filter: is it clogged, and when was it last changed? Clogged — change it.
- Blow through or check the sensor tubes: if they are clogged with dust or water, the drop reading will be false.
- FMI 0, 3, 4 (KamAZ, Mercedes: sensor or drop out of spec): unplug the sensor connector and check the wire.
- The Renault line in the factory table refers to the clutch sensor, not to the filter. We do not use it here.
Common causes — from most to least frequent
- Clogged air filter.
- Clogged sensor tube or water in it.
- Oxidised sensor connector.
- The sensor itself.
KAMAZ-5490Mercedes-BenzRenault TrucksZF AS-Tronic
KAMAZ-5490 (Mercedes, K-line)
FMI is per the block maker's own table, not the J1939 table below.
| FMI 0 | Air filter restriction sensor: differential pressure too high. K-line code on KamAZ-5490: ADM3 10800. |
| FMI 3 | Air filter restriction sensor: open circuit. K-line code on KamAZ-5490: ADM3 10803. |
| FMI 4 | Air filter restriction sensor: short to ground. K-line code on KamAZ-5490: ADM3 10804. |
Mercedes-Benz
| FMI 0 | Air Filter Restriction High |
| FMI 2 | Air Filter Sensor plausibility error |
| FMI 3 | Air Filter diff.-pressure Sensor or switch shorted to Ubat |
| FMI 4 | Air Filter diff.-pressure Sensor or switch shorted to GND |
Renault Trucks
| FMI 2 | Clutch sensor supply out of allowed limits. Repair: Run the diagnostic check of the clutch actuator. Check the wiring between the Astronic and the components (X1B/15). Switch the ignition off, switch it on again and repeat the test. If the fault persists, replace the control unit. |
ZF AS-Tronic gearbox
FMI is per the block maker's own table, not the J1939 table below.
| FMI 2 | Clutch sensor supply voltage out of range (output AU). |
What FMI means in J1939
Can I keep driving
Safe to drive. Below — how much time you have and what happens if you keep going.
What happens if you keep driving
Boost is not reaching its target: turbo, intercooler or intake. The engine compensates with mixture and runs hotter than usual.
You will lose pull, burn more fuel and add overheating on long climbs. If you hear a whine or a whistle from the turbo, stop — the wheel is breaking up.
This is an electrical fault: an open, a short or a bad contact in the sensor circuit. The value it measures is most likely fine. You can drive. But until the circuit is repaired this system runs blind and cannot warn you about a real failure.
What to check on the spot
Inspect the air filter and charge-air hoses: leaks and cracks produce exactly these codes.
Nearby: intake / boost
- SPN 51Engine throttle valve position
- SPN 102Intake manifold pressure (boost)
- SPN 105Intake manifold air temperature
- SPN 106Engine Intake Air Pressure
- SPN 132Intake mass air flow
- SPN 411EGR Differential Pressure
- SPN 729Intake Air Heater Driver #1
- SPN 730Intake Air Heater Driver #2
- SPN 2791EGR Valve Control
- SPN 3464Throttle Actuator Control Command 1
Makes with this code
Related problems
- Black exhaust smoke
What SPN 107 is measuring
SPN 107 reports the pressure difference across the engine air filter. A sensor compares the pressure before and after the filter element; as dust loads the filter, the difference rises. The engine computer uses it to warn the driver that the filter needs service.
- FMI 15 (and 0 or 16 on some engines) - restriction above normal. The filter is blocked or the sensor reads high.
- SPN 107 FMI 15 is by far the most searched value and in most cases means exactly what it says: the element is loaded.
- FMI 3 and 4 - the sensor circuit is open or shorted high or low.
- FMI 2 - an implausible reading, for example the difference stays at zero while the engine is under load.
Why it matters and how to check
A restricted air filter starves the engine of air: black smoke, lost power, higher fuel use and, on engines with EGR or a particulate filter, more soot and more regeneration. A commonly quoted service limit for heavy-duty diesels is about 6 kPa (25 inches of water), but engines differ, so use your manual.
1. Look at the element. Tap it gently; heavy dust, oil or a wet filter confirms the code. Check the housing seals and the intake hose for leaks and cracks: unfiltered air is worse than a clogged filter.
2. If the filter is new or clean and the code stays, check the sensor hose or port. A cracked or blocked sensing tube gives a false reading.
3. For FMI 3 and 4, inspect the sensor connector and the wiring.
4. Replace the sensor only when the filter, housing and hoses are good.
Can you keep driving?
A warning at FMI 15 is not an emergency: you can reach a service point, ideally with the filter changed soon. If power is falling or the exhaust is black, do not drive hard. The risk is dust entering the engine if the housing is damaged, not the code itself.
Questions and answers
Can I clean the filter with compressed air?
Some manufacturers allow it for dry dust with low pressure from the inside out, but paper filters are best replaced. Follow the manufacturer's procedure.
The filter is new but SPN 107 FMI 15 remains. Why?
The sensor port or hose may be blocked, the housing may not seal, or the code was stored earlier and not cleared.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.