SPN 1209 FMI 2 — Exhaust gas pressure sensor erratic
What it means: Exhaust gas pressure sensor erratic.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Inspect line
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Indianapolis, IN
Closest first. Tell them SPN 1209 FMI 2 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Indianapolis, IN · (317) 789-5002
- 0.0 mi away — based in Indianapolis, IN · (317) 300-7000
- 0.0 mi away — based in Indianapolis, IN · (317) 646-8208
Applies to: Paccar · Volvo
What SPN 1209 FMI 2 means
Exhaust gas pressure sensor erratic.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Sensor line plugged
- Failed sensor
- Sensor line plugged with soot
- Sensor failed
First moves (roadside)
- Inspect line
- Clean sensor line
- Bench check
FAQ
Exhaust gas pressure sensor erratic.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Sensor line plugged. Other possibilities include Failed sensor; Sensor line plugged with soot; Sensor failed.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 1209 FMI 2, or share the same subsystem.
- Exhaust back pressure sensor — high voltage (SPN 1209 FMI 3)
- Engine Protection — Power Derate Active (SPN 1569 FMI 31)
- Intake Manifold (Charge Air) Temp — High (SPN 105 FMI 0)
- Turbo Boost Pressure — High / Overboost (SPN 1127 FMI 16)
- Boost pressure high (SPN 102 FMI 0)
- Boost sensor — voltage low (SPN 102 FMI 4)
- Intake manifold temp — voltage high (SPN 105 FMI 3)
- Intake manifold temp — voltage low (SPN 105 FMI 4)
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.