P249A — Particulate Filter Differential Pressure Too Low at Idle
What it means: Particulate Filter Differential Pressure Too Low at Idle.
How serious / can you keep driving: Caution. Limp to the next safe stop.
Check first: Compare idle pressure to spec
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Baltimore, MD
Closest first. Tell them P249A 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 Baltimore, MD · (443) 680-6789
- 0.0 mi away — based in Baltimore, MD · (410) 544-3888
- 24 hour Mobile Diesel Truck Engine Repair DEF Repairs On Site Services Road Service Laptop Diagnostic Tractors & Dump Truck☎ Call0.0 mi away — based in Baltimore, MD · (443) 591-3631
Seen on: Heavy Truck/Diesel
What P249A means
Particulate Filter Differential Pressure Too Low at Idle. Common causes: DPF pressure sensor reading lower than expected.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- DPF pressure sensor reading lower than expected
- Cracked DPF substrate
- sensor port blocked
First moves (roadside)
- Compare idle pressure to spec
- inspect DPF for cracking
- check sensor ports
FAQ
Particulate Filter Differential Pressure Too Low at Idle. Common causes: DPF pressure sensor reading lower than expected.
Caution — Limp to the next safe stop.
The most common cause is: DPF pressure sensor reading lower than expected. Other possibilities include Cracked DPF substrate; sensor port blocked.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside P249A, or share the same subsystem.
- SCR Operator Inducement — Severe Derate Active (SPN 5246 FMI 0)
- Aftertreatment 1 Diesel Particulate Filter Differential Pressure - Data Valid But Above Normal Operating Range, Most Severe Level (DPF severely restricted / plugged) (SPN 3251 FMI 0)
- Aftertreatment 1 Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range, Most Severe Level (DEF quality/concentration incorrect) (SPN 4364 FMI 1)
- DPF Differential Pressure — Data Erratic (SPN 3251 FMI 2)
- DEF Dosing Unit — Not Responding Properly (SPN 3361 FMI 7)
- SCR Conversion Efficiency — Below Threshold (SPN 4364 FMI 18)
- DEF Quality — Out of Spec (SPN 4094 FMI 31)
- EGR Temperature — Too High (SPN 412 FMI 0)
Same symptom: Regen problems
Other codes that block a regen or come back as soot load climbing.
- DPF Soot Accumulation Restriction (P2460) · Aftertreatment & Emissions
- DPF inlet temp sensor — voltage high (SPN 3241 FMI 3) · Aftertreatment & Emissions
- DPF outlet temp erratic (SPN 3242 FMI 2) · Aftertreatment & Emissions
- DPF outlet temp sensor — voltage high (SPN 3246 FMI 3) · Aftertreatment & Emissions
- DPF differential pressure — voltage high (SPN 3251 FMI 3) · Aftertreatment & Emissions
- DPF differential pressure — voltage low (SPN 3251 FMI 4) · Aftertreatment & Emissions
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.