International Truck Engine History and the A26
International Trucks (Navistar International) has a complex engine history relevant to fault code interpretation. The MaxxForce engine family (MaxxForce 11, MaxxForce 13, and earlier) used heavy EGR for NOx control instead of SCR in the 2010–2014 era — a strategy that resulted in significant reliability issues. Most International trucks produced after approximately 2014–2015 transitioned to models with Cummins engines.
The current International A26 engine, introduced around 2017, represents International's return to an in-house engine for Class 8 applications. The A26 uses a conventional SCR-based aftertreatment system aligned with modern J1939 conventions. It is distinct from the MaxxForce family and requires International Servicemaxx for diagnosis — not legacy MaxxForce tooling.
Diamond Logic Body Controller and Source Address Complexity
International trucks use the Diamond Logic body controller system, which integrates cab functions, lighting, PTO, auxiliary loads, and vehicle customization into a single controller. Diamond Logic generates its own fault codes, which appear on the driver display alongside engine and drivetrain codes. Identifying whether a fault came from the engine, the body controller, or another module requires the source address or a diagnostic tool.
Servicemaxx is International's OEM diagnostic software, providing access to the engine ECM, aftertreatment system, Diamond Logic body controller, and other chassis modules. For vehicles with Cummins engines installed by International (common in 2014–2017 era trucks), Cummins Insite handles the engine while Servicemaxx handles the chassis.
MaxxForce vs. A26 Fault Code Differences
MaxxForce-era International trucks used EGR as the primary NOx control mechanism and had significant technical service bulletin activity related to EGR cooler failures, injector failures, and EGR system fault cascades. Fault code interpretation for these engines requires the specific MaxxForce documentation set. The SPN/FMI codes may follow J1939 structure, but the MaxxForce-specific calibration responses and repair procedures are distinct from modern J1939 engines.
A26 fault code interpretation follows standard J1939 conventions more closely than the MaxxForce era. However, International uses manufacturer-specific extensions and Servicemaxx parameters that go beyond the public J1939 standard. A26 engines with persistent aftertreatment faults follow a calibration-specific inducement sequence managed through Servicemaxx.
Using This Site for International Truck Context
Pages on this site that cover International or Navistar fault codes focus primarily on the A26 and current J1939-aligned architecture. Coverage of MaxxForce-era codes is limited given the complexity of that platform and the distinct diagnostic tooling it requires.
For International trucks equipped with Cummins engines (common in 2014–2017 configurations), the Cummins fault code pages on this site apply to the engine-side codes. For Diamond Logic body controller codes, International Servicemaxx and the current OEM documentation are the appropriate references.
Fault Code Coverage on This Site
International truck coverage focuses on the A26 (9.0-liter, introduced 2017) used in current International LT and RH Series trucks. Engine performance and protection fault categories covered include: SPN 100 FMI 1 (engine oil pressure low, A26); SPN 102 FMI 17 (boost pressure low, A26); and SPN 110 FMI 0 (coolant temperature high, A26). MaxxForce-era engines (MaxxForce 11, MaxxForce 13) are not covered on this site due to the complexity of that platform's distinct calibration and diagnostic tool requirements.
Aftertreatment fault categories covered for the A26 include: SPN 3251 FMI 0 (DPF differential pressure high); SPN 3364 FMI 1 (DEF quality low); SPN 5246 FMI 31 (SCR efficiency below threshold); and SPN 1569 FMI 31 (engine protection torque derate active). For International trucks built in the 2014–2017 period with Cummins ISX or X15 engines, the Cummins section covers the engine fault codes applicable to those vehicles. All A26 pages on this site reference Navistar/International service publications and the SAE J1939 standard.
Related Pages
Related Fault Code Pages
Official Resources
- International Trucks Service and Parts — International Trucks service support portal for A26 engine and Diamond Logic body controller service information. International Servicemaxx is the OEM diagnostic tool for current LT and RH Series trucks.
- Navistar Engine DTC Body Builder References — Navistar public engine diagnostic trouble code index for body builder and fleet reference. Covers A26 and related Navistar engine fault code cross-references.
Sources
- Navistar Engine Diagnostic Trouble Code Body Builder References Navistar / International Truck Body Builder · oem · accessed 2026-05-05 · confidence medium
Source: Navistar / International Truck Body Builder, Navistar Engine Diagnostic Trouble Code Body Builder References. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium
Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
Does International use Navistar or Cummins engines now, and does that affect which fault code system applies?
International (Navistar) has produced several engine families, including the MaxxForce series and the current A26. Some International trucks have also been sold with Cummins engines, particularly after Navistar's earlier MaxxForce emissions issues. The engine fault codes depend entirely on the engine installed: A26 codes use Navistar's Diamond Logic and International Servicemaxx; Cummins-equipped trucks use Insite. Verify the engine family before selecting a diagnostic tool.
Can a fault code from an International body controller look the same as an engine code on the dash?
Yes. International trucks use a Diamond Logic body controller that integrates cab, chassis, and PTO functions. Fault codes from the body controller can appear alongside engine codes on the driver display. Servicemaxx is the OEM tool that identifies which module reported a given code. Without source address context, separating chassis codes from engine codes on the display alone is not reliable.
Do older MaxxForce fault codes use the same format as current International A26 engine codes?
MaxxForce engines (MaxxForce 11, 13, and earlier families) had engine-specific codes, some of which differed from J1939 standard conventions. Current A26 engines align more closely with J1939 SPN/FMI conventions. Moving from a MaxxForce-era truck to an A26 model involves different fault code tables, different diagnostic tools, and different aftertreatment strategies.
Which International engine models and fault codes are covered on this site?
Coverage focuses on the International A26 engine in LT Series, RH Series, and HX Series trucks. A26 covered SPNs include: SPN 100 FMI 1 (oil pressure critically low), SPN 102 FMI 1 (boost pressure below normal), SPN 110 FMI 0 (coolant temperature high), SPN 3251 FMI 0 (DPF restriction), SPN 3364 FMI 1 (DEF quality below threshold), SPN 5246 FMI 31 (SCR efficiency below threshold), and SPN 1569 FMI 31 (aftertreatment inducement derate). All A26 pages reference International ServiceMaxx as the diagnostic tool path and note Diamond Logic integration context. MaxxForce-era codes are not specifically covered — those engines require separate factory documentation and are not included in the modern J1939-aligned fault code pages on this site.