The A26 replaced the N13 in 2017 and changed everything: MAN-derived block, single turbo, consolidated aftertreatment. Its codes look familiar (SPN/FMI) but the root causes differ from the MaxxForce era — this list is A26-specific.
How International A26 fault codes work
A26 codes report through NavKal or any J1939 scanner as standard SPN/FMI. Navistar overlays its own descriptions in NavKal — the guided tests there are worth having for the aftertreatment and fuel system.
Most-searched International A26 codes
These are the codes technicians look up most. Every row links to a full code page with symptoms, ranked causes and step-by-step diagnostics.
| Code | Meaning | Severity | Common fix |
|---|---|---|---|
| SPN 3216 FMI 4 | NOx sensor low | High | Sensor/harness |
| SPN 5246 FMI 0 | SCR derate inducement | Critical | Root repair + NavKal reset |
| SPN 4339 FMI 0 | SCR efficiency low | High | Guided SCR diag |
| SPN 157 FMI 3 | Injector metering rail pressure high | High | Fuel system diag |
| SPN 641 FMI 7 | Turbo actuator | Medium | Calibration/replacement |
| SPN 3251 FMI 0 | DPF pressure high | High | Forced regen then inspect |
| SPN 3226 FMI 4 | Aft NOx sensor low | High | Sensor/harness |
Tools that read and clear International A26 codes
NavKal is the native platform with A26 programming and guided tests. Multi-brand scanners handle read/clear and regens well on the A26 — it's one of the better-covered new engines on Jaltest/JPRO. Programming remains NavKal territory.
Frequently Asked Questions
Is the A26 related to MaxxForce?
No — clean-sheet MAN-derived design, unrelated architecture. MaxxForce experience doesn't transfer; treat it as a new engine with its own fault behaviors.
A26 vs Cummins X15 for fleet reliability — what do the codes say?
Field data shows the A26's aftertreatment faults concentrate in NOx sensors early, then stabilize. The X15 has broader but shallower fault patterns. Both are solid; the A26's NavKal tooling is cheaper to own.