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SPN 190 FMI 2 — Engine speed sensor — erratic
SeriousEnginePower derate likely — plan to stop soon
Applies to: Detroit · Navistar · Paccar · Volvo
Engine speed sensor — erratic.
Don't risk it — get a diesel tech on the truck.
Your SPN/FMI rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Crank sensor failing
- Tone wheel damage
- Air gap
- Harness issue
- Crank sensor
- Tone wheel
First moves (roadside)
- Check sensor air gap
- Inspect tone wheel
- Resistance check
- Inspect sensor
- Air gap inspection
- Resistance
- Sensor air gap and resistance
FAQ
What does SPN 190 FMI 2 mean?
Engine speed sensor — erratic.
How serious is SPN 190 FMI 2?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of SPN 190 FMI 2?
The most common cause is: Crank sensor failing. Other possibilities include Tone wheel damage; Air gap; Harness issue; Crank sensor; Tone wheel.
Can I keep driving with SPN 190 FMI 2?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.