DPF Differential Pressure Sensor
Location, hose connections, test procedure, and related fault codes for the DPF delta-P sensor on Class 8 diesel trucks.
Last updated: 2026-09-20
Overview
The DPF differential pressure sensor measures the pressure difference across the DPF filter. The ECM uses this reading to calculate soot loading and determine when regeneration is needed. Two small hoses connect the sensor to the DPF inlet and outlet.
Sensor Locations by Platform
Cummins X15
Mounted on DPF canister, driver side. Two small rubber hoses run to the sensor ports — one to DPF inlet, one to DPF outlet.
Check hoses for plugging or cracks before replacing sensor.
PACCAR MX-13
Passenger side, on DPF housing bracket. Often near DPF outlet temperature sensor.
MX-13 DPF pressure sensor hoses can plug with soot at high mileage.
Detroit DD15
Mounted on passenger side of aftertreatment housing, near DPF inlet. Two hose ports connect to DPF inlet and outlet.
DD15 DPF pressure sensor hoses are prone to cracking at high mileage.
Volvo/Mack MP8
Mounted on aftertreatment housing. Two hose ports connect to DPF inlet and outlet.
Check hose routing — kinked hoses cause false high readings.
DieselVision™ identifies sensor labels and connector pin numbers — upload a close-up photo and the system maps pins automatically.
Connector Pinout
| Pin | Function | Specification |
|---|---|---|
| A | 5V Reference | 4.75–5.25V |
| B | Ground (Signal Return) | <0.1V to chassis ground |
| C | Signal Output | 0.5V at 0 kPa differential, 4.5V at 50 kPa differential |
Test Procedure
Read DPF differential pressure live data at idle
Expected: Normal: 0.5–3 kPa at idle with clean DPF. High: >10 kPa indicates high soot loading
Tool: OEM diagnostic software
Inspect DPF pressure sensor hoses for plugging, kinks, or cracks
Expected: Hoses should be clear, round, and undamaged. Plugged hoses cause false high readings
Tool: Visual inspection
Disconnect both hoses from sensor — read differential pressure
Expected: With both hoses disconnected, reading should drop to near 0 kPa. If still high = sensor failure
Tool: OEM diagnostic software
Measure 5V reference voltage at harness connector
Expected: 4.75–5.25V between pin A and pin B
Tool: Multimeter
Check signal wire for short to ground
Expected: >1 MΩ between pin C and chassis ground
Tool: Multimeter
Blow through hoses to verify they are clear
Expected: Air should flow freely through both hoses. Restriction = plugged hose
Tool: Compressed air (low pressure)
Common Failure Modes
- •Hose plugging with soot — most common cause of false high readings
- •Hose cracking or disconnection — causes false low or erratic readings
- •Sensor internal failure — signal stuck high or low
- •Connector corrosion causing intermittent signal
- •Hose kinked during service — causes false high reading
Frequently Asked Questions
Where is the DPF differential pressure sensor located?
The DPF differential pressure sensor is mounted on or near the DPF canister. Two small hoses connect it to the DPF inlet and outlet ports.
What causes a false high DPF pressure reading?
The most common cause is plugged pressure hoses. Disconnect both hoses from the sensor — if the reading drops to near zero, the hoses are plugged, not the sensor.
What is a normal DPF differential pressure at idle?
With a clean DPF at idle, differential pressure should be 0.5–3 kPa. Readings above 10 kPa indicate high soot loading or a plugged hose.
What fault codes are caused by a failed DPF pressure sensor?
Common fault codes include SPN 3251 FMI 0 (critical high pressure), SPN 3251 FMI 16 (above normal), and SPN 3719 FMI 16 (DPF soot load above normal).
Snap a photo of your scan tool screen and let Diesel Vision interpret the fault instantly — no manual code lookup required.
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