Detroit DD15 Diagnostics (2010–present)
Freightliner and Western Star trucks with the 14.8-liter Detroit DD15 (EPA10, GHG14, GHG17): high-pressure common rail, cooled EGR, and DOC + DPF + SCR with DEF, managed by the MCM, ACM and CPC. J1939 SPN/FMI fault codes, not OBD-II P-codes.
Common symptoms
- Derate to 5 MPH (SCR / DEF Fault) — Detroit DD15 The truck limits speed to 5 mph due to aftertreatment inducement on a Detroit DD15. This is the final stage of SCR/DEF protection and is never the root cause…
- EGR Flow Problems — Detroit DD15 Diagnostic guide for EGR flow problems on Detroit DD15 (2010–present).
- Frequent Regens or DPF Restriction — Detroit DD15 Diagnostic guide for frequent regenerations and DPF restriction on Detroit DD15 (2010–present).
- Hard Start or Stalling — Detroit DD15 Hard starting or stalling on a Detroit DD15 is often fuel rail pressure related or a sensor supply voltage pulled low by a shorted sensor or harness.
- Loss of Power — Detroit DD15 Loss of power on a Detroit DD15 is commonly an aftertreatment derate, a restricted DPF, EGR flow problem, or a fuel rail pressure issue. Read codes from the…
- SPN 157 FMI 2 — Injector Metering Rail 1 Pressure – Erratic, Intermittent or Incorrect — Detroit DD15 Diagnostic reference for Detroit DD15 (2010–present) with SAE J1939 SPN/FMI reported by MCM/ACM/CPC. Focus on diagnosing the cause of erratic rail pressure…
- SPN 2659 FMI 0 — EGR Mass Flow Rate – Above Normal, Most Severe (EGR flow target error, high flow) — Detroit DD15 Measured EGR flow is above the target on Detroit DD15 (2010–present).
- SPN 2659 FMI 1 — EGR Mass Flow Rate – Below Normal, Most Severe (EGR flow target error, low flow) — Detroit DD15 Measured EGR flow is below the target on Detroit DD15 (2010–present).
- SPN 3216 FMI 18 — Aftertreatment Intake NOx – Below Normal, Moderately Severe — Detroit DD15 Diagnostic reference for Detroit DD15 (2010–present) with SAE J1939 SPN/FMI reporting. Focuses on diagnosing the intake NOx sensor reading low condition…
- SPN 3226 FMI 20 — Aftertreatment Outlet NOx – Data Drifted High — Detroit DD15 SPN 3226 FMI 20 on Detroit DD15 (2010–present) means the outlet NOx sensor reading has drifted high. The ACM/MCM/CPC reports the fault via J1939. Diagnose…
- SPN 3251 FMI 0 — Aftertreatment DPF Differential Pressure – Above Normal, Most Severe — Detroit DD15 Detroit DD15 (2010–present) diagnostic reference for SPN 3251 FMI 0.
- SPN 3597 FMI 4 — ECU Power Output Supply Voltage 1 – Voltage Below Normal — Detroit DD15 Diagnostic reference for Detroit DD15 (2010–present) when the MCM reports SPN 3597 FMI 4. Use to identify why the controller supply output is low and isolate…
- 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.
- SPN 3719 FMI 16 — Aftertreatment DPF Soot Load – Above Normal, Moderately Severe — Detroit DD15 SPN 3719 FMI 16 is a Detroit DD15 aftertreatment fault for DPF soot load above normal, moderately severe. The ACM/MCM calculates soot load from DPF…
- SPN 3720 FMI 16 — Aftertreatment DPF Ash Load – Above Normal, Moderately Severe — Detroit DD15 SPN 3720 FMI 16 on Detroit DD15 (2010–present) indicates the calculated DPF ash load is above normal, moderately severe. Ash accumulates over time and does not…
- SPN 4364 FMI 18 — Aftertreatment SCR Conversion Efficiency – Below Normal, Moderately Severe — Detroit DD15 Diagnostic reference for Detroit DD15 (2010–present) with SAE J1939 SPN/FMI.
- SPN 5246 FMI 0 — Aftertreatment SCR Operator Inducement Severity – Most Severe — Detroit DD15 SPN 5246 FMI 0 is the most severe operator inducement for the SCR system on Detroit DD15 (2010–present). It is a response code, not a root cause, and indicates…