A26 Engine Fault
International Commercial Truck
Severity: ModerateWhat Does This Error Mean?
An International amber engine warning indicates an A26 or S13 engine fault stored in the ECM. A J1939 scan tool reads SPN and FMI codes. Navistar's diagnostic tool (Diamond Logic Builder, ServiceMaxx) is needed for detailed work.
Affected Models
- International LT
- International RH
- International HV
- International HX
- International MV
- International CV
Common Causes
- A26 / S13 engine sensor fault (boost, EGR, NOx, etc.)
- EGR valve carbon buildup or actuator failure
- Variable geometry turbocharger (VGT) actuator fault
- DPF or DOC differential pressure sensor failure
- NOx sensor inlet or outlet failure
How to Fix It
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Check warning urgency.
Amber check engine = stored fault, usually drivable. Red stop engine or rapid-flash amber = serious — pull over safely as soon as practical.
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Read codes with a J1939 scanner.
Connect a heavy-duty scanner (such as JPRO, Noregon DLA, or Texa) to the J1939 connector under the dash. The SPN identifies the component and FMI identifies the fault type.
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Inspect basic items.
Verify oil, coolant, and DEF levels. Look for visible leaks, disconnected hoses, and damaged sensors. Many fault codes have simple physical causes.
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Take to a Navistar-authorised shop.
ServiceMaxx is required for many advanced functions — actuator tests, EGR resets, parameter changes. An International dealer or Navistar-trained shop can perform full diagnostics and proper repairs.
When to Call a Professional
International dealers and Navistar-authorised shops use ServiceMaxx and Diamond Logic Builder for full diagnostics. For complex faults, especially after-treatment-related, professional service is the most efficient route.