Cummins ISX15 Diagnostics (2010–2017)

Class 8 trucks with the 15-liter Cummins ISX15 (CM2250/CM2350): XPI common-rail fuel system, a variable-geometry turbo, cooled EGR, and DOC + DPF + SCR with DEF. Cummins fault codes with their J1939 SPN/FMI, not OBD-II P-codes.

Common symptoms

• DEF Derate or 5 MPH Speed Limit — Cummins ISX15 A Cummins ISX15 (2010–2017) that enters SCR operator inducement and limits speed to 5 mph, often with FC 3712 and FC 3714 present. The symptom is an effect of…
• Frequent Regens or High DPF Soot Load — Cummins ISX15 A diagnostic reference for Cummins ISX15 (2010–2017) engines showing frequent regenerations or a high DPF soot load.
• Hard Start or No Start — Cummins ISX15 A concise diagnostic reference for hard start or no start on the Cummins ISX15 (2010–2017) with CM2250/CM2350 ECM and XPI high-pressure common rail.
• Loss of Power — Cummins ISX15 Diagnostic reference for loss of power on Cummins ISX15 (2010–2017) with CM2250/CM2350 ECM. Covers derate, fuel rail pressure, VGT turbo and EGR-related power…
• Overheating or EGR Cooler Problems — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) when the engine runs hot or EGR cooler issues are suspected.

• FC 1682 — Aftertreatment DEF Dosing Unit Input Lines – Condition Exists (SPN 3362 FMI 31) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 1682.
• FC 1691 — Aftertreatment Diesel Oxidation Catalyst Conversion Efficiency – Below Normal — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 1691.
• FC 1712 — Aftertreatment DEF Tank Heater – Below Normal (SPN 3363 FMI 18) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 1712.
• FC 1866 — EGR Delta Pressure – Erratic, Intermittent or Incorrect (SPN 411 FMI 2) — Cummins ISX15 A diagnostic reference for Cummins ISX15 (2010–2017, CM2250/CM2350) FC 1866.
• FC 1867 — EGR Temperature – Erratic, Intermittent or Incorrect (SPN 412 FMI 2) — Cummins ISX15 A diagnostic reference for Cummins ISX15 (2010–2017) FC 1867. Use it to identify why the ECM sees an erratic or implausible EGR temperature signal and to…
• FC 2265 — Electric Lift Pump Circuit – Voltage Above Normal (SPN 1075 FMI 3) — Cummins ISX15 The ECM sees voltage on the electric lift pump circuit above the normal range or an open condition. On Cummins ISX15 (2010–2017) the electric lift pump…
• FC 2266 — Electric Lift Pump Circuit – Voltage Below Normal (SPN 1075 FMI 4) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 2266.
• FC 2311 — Electronic Fuel Injection Control Valve Circuit – Condition Exists (SPN 633 FMI 31) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) CM2250/CM2350 with XPI high-pressure common rail.
• FC 2346 — Turbocharger Turbine Intake Temperature – Above Normal (SPN 2789 FMI 15) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 2346.
• FC 2372 — Fuel Filter Differential Pressure – Above Normal (SPN 95 FMI 16) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 2372.
• FC 2639 — Aftertreatment DPF Differential Pressure – Above Normal, Least Severe (SPN 3251 FMI 15) — Cummins ISX15 Cummins ISX15 (2010–2017) diagnostic reference for FC 2639 (SPN 3251 FMI 15).
• FC 2771 — Aftertreatment Outlet NOx Sensor – Abnormal Update Rate (SPN 3226 FMI 9) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 2771.
• FC 2962 — EGR Temperature – Above Normal, Moderately Severe (SPN 412 FMI 16) — Cummins ISX15 EGR gas temperature after the cooler is higher than expected on Cummins ISX15 (2010–2017) with CM2250/CM2350 ECM, cooled EGR and DOC+DPF+SCR aftertreatment.
• FC 2963 — Engine Coolant Temperature – Above Normal, Least Severe (SPN 110 FMI 15) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) ECM CM2250/CM2350.
• FC 3253 — Aftertreatment DPF Intake Temperature – Above Normal, Moderately Severe (SPN 3242 FMI 16) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) CM2250/CM2350 with Cummins FC 3253.
• FC 3498 — Aftertreatment DEF Tank Level – Below Normal, Moderately Severe (SPN 1761 FMI 18) — Cummins ISX15 Cummins ISX15 (2010–2017) diagnostic reference for FC 3498.
• FC 3543 — NOx Limits Exceeded Due to Insufficient Reagent Quality (SPN 4094 FMI 31) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 3543.
• FC 3582 — Aftertreatment SCR Catalyst Conversion Efficiency – Below Normal (SPN 4364 FMI 18) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 3582.
• FC 3596 — Aftertreatment DEF Pressure – Erratic, Intermittent or Incorrect (SPN 4334 FMI 2) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 3596.
• FC 3712 — Aftertreatment SCR Operator Inducement – Most Severe Level (SPN 5246 FMI 0) — Cummins ISX15 Cummins ISX15 (2010–2017) diagnostic reference for FC 3712.
• FC 3714 — Engine Protection Torque Derate – Condition Exists (SPN 1569 FMI 31) — Cummins ISX15 The ECM is applying an engine protection torque derate. On Cummins ISX15 (2010–2017) this code is informational: another active fault caused the derate…
• FC 3727 — High-Pressure Common Rail Fuel Pressure Relief Valve – Not Responding (SPN 5571 FMI 7) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 3727.
• FC 3867 — Aftertreatment DEF Quality – Below Normal (SPN 3364 FMI 18) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 3867.
• FC 3936 — Aftertreatment Diesel Particulate Filter System – Above Normal (SPN 3936 FMI 15) — Cummins ISX15 A diagnostic reference for Cummins ISX15 (2010–2017) FC 3936. Use it to identify why the ECM reports DPF system above normal and to decide the next checks…
• FC 418 — Water-In-Fuel Indicator – Above Normal (SPN 97 FMI 15) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) FC 418.
• FC 4572 — Aftertreatment DEF Tank Temperature – Abnormal Update Rate (SPN 3031 FMI 9) — Cummins ISX15 The ECM is not receiving DEF tank temperature updates at the expected rate on a Cummins ISX15 (2010–2017).
• FC 4677 — Aftertreatment DEF Tank Level – Abnormal Update Rate (SPN 1761 FMI 9) — Cummins ISX15 Cummins ISX15 (2010–2017) diagnostic reference for FC 4677 (SPN 1761 FMI 9).
• FC 559 — Injector Metering Rail 1 Pressure – Below Normal (SPN 157 FMI 18) — Cummins ISX15 Diagnostic reference for Cummins ISX15 (2010–2017) CM2250/CM2350 with XPI high-pressure common rail.
• FC 6254 — Aftertreatment SCR Operator Inducement Severity – Moderately Severe Level (SPN 5246 FMI 16) — Cummins ISX15 Cummins ISX15 (2010–2017) diagnostic reference for FC 6254.
• FC 687 — Turbocharger 1 Speed – Below Normal (SPN 103 FMI 18) — Cummins ISX15 Turbocharger speed is lower than expected on Cummins ISX15 (2010–2017) with a single VGT and electronic actuator.