SPN 3610 FMI 2 — Aftertreatment DPF Outlet Pressure – Erratic, Intermittent or Incorrect — Detroit DD15

Diagnostic reference for Detroit DD15 (2010–present) with SAE J1939 SPN/FMI.

Updated October 15, 2026

What it means

The DPF outlet pressure reading is erratic or implausible. On Detroit DD15 the ACM monitors aftertreatment pressure sensors; this code is reported by the MCM/ACM/CPC on the DD15 platform.¹

Most likely causes

1. Plugged or cracked DPF outlet pressure sensor line causing erratic pressure signal — Moisture, soot or debris can block or crack the small sense line to the DPF outlet pressure sensor, producing an intermittent or implausible reading.¹
2. Failing DPF outlet pressure sensor — Sensor drift or internal fault makes the outlet pressure signal erratic or out of range.¹
3. Wiring or connector fault to the DPF outlet pressure sensor — Chafed, corroded or loose wiring/connectors introduce noise or intermittent loss of signal to the ACM.¹

How to diagnose

1. Verify active SPN 3610 FMI 2 and check for related aftertreatment codes (e.g., DPF differential pressure SPN 3251, soot load SPN 3719/3720) to separate a true pressure issue from a sensor/electrical fault.
2. Inspect the DPF outlet pressure sensor and its sense line for cracks, kinks, blockage, moisture or soot contamination; look for signs of exhaust leaks near the tap.
3. Check sensor electrical connector for corrosion, moisture and proper seating; inspect harness for chafing or heat damage along the aftertreatment routing.
4. With key on/engine off, compare DPF outlet pressure PID to expected atmospheric baseline and watch for erratic jumps; compare to DPF inlet pressure behavior if available.
5. If the sense line and wiring are intact, monitor live outlet pressure during a steady cruise and during a regeneration event for plausibility versus engine load and DPF differential pressure.
6. If the signal remains erratic with a clean line and good wiring, the pressure sensor is suspect and should be tested against a known-good unit or replaced per Detroit service information.

Common mistake to avoid

Cleaning or replacing the DPF before checking its pressure sensor and tubes. Cracked, melted, plugged or wet sensor tubes, or a failing sensor, can set DPF codes while the filter itself is fine. They are cheap to check; clear and verify them before touching the filter. Source: FleetRabbit — P2002 DPF efficiency code causes and fixes.

Parts and tools you may need

• Diagnostic scan tool capable of Detroit MCM/ACM/CPC J1939 PIDs
• Digital multimeter
• Inspection mirror and flashlight
• Compressed air and soft brush for sense line cleaning
• Replacement DPF outlet pressure sensor and sense line kit (Detroit part numbers per VIN)
• Dielectric grease
• Safety gloves and eye protection

Tools you’ll need

• digital multimeter — Checks sensor supply voltage, ground continuity, and signal return for opens/shorts that cause erratic SPN 3610 FMI 2 readings.
• OBD-II diagnostic scan tool — Reads active SPN 3610 FMI 2 and related aftertreatment PIDs to compare DPF outlet pressure baseline and live plausibility during cruise and regen.
• hand vacuum/pressure pump with gauge — Tests the DPF outlet pressure sensor and sense line for leaks, blockage, or sticking that produce implausible pressure signals.
• inspection mirror and flashlight — Allows visual inspection of the DPF outlet pressure sensor, sense line, and exhaust tap for cracks, soot plugging, moisture, and heat damage.

Rough cost and difficulty

Typical US independent-shop figures; labor runs about $140–$200 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If the code persists after line and connector service, or if DPF differential pressure is high with soot/ash load codes, have the aftertreatment system evaluated by a Detroit authorized shop. High-pressure fuel or exhaust service requires proper training and safety controls. Do not attempt repairs that involve opening high-pressure fuel or exhaust components without qualified support.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources