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International International A26 repair, fault codes & roadside

International (Navistar)12.4L

The International A26 is a 12.4L inline-six derived from the MAN D26, used across the LT and LoneStar. It's a clean-sheet design that left the troubled MaxxForce era behind; its common roadside faults are the usual aftertreatment and EGR codes.

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Common International A26 faults

Relevant fault codes (International A26)

These heavy-duty SPN/FMI codes commonly show up on engines like the International A26. Tap one for a plain-English meaning, severity, likely causes, and roadside first moves.

SPN 3251 FMI 2DPF Differential Pressure — Data ErraticAftertreatment (DPF)SPN 3361 FMI 7DEF Dosing Unit — Not Responding ProperlyAftertreatment (SCR/DEF)SPN 4364 FMI 18SCR Conversion Efficiency — Below ThresholdAftertreatment (SCR/DEF)SPN 4094 FMI 31DEF Quality — Out of SpecAftertreatment (SCR/DEF)SPN 1761 FMI 1DEF Tank Level — LowAftertreatment (SCR/DEF)SPN 5246 FMI 0SCR Operator Inducement — Severe Derate ActiveAftertreatment (SCR/DEF)SPN 100 FMI 1Engine Oil Pressure — Extremely LowLubricationSPN 110 FMI 0Engine Coolant Temperature — Too HighCoolingSPN 102 FMI 3Boost Pressure Sensor — Voltage HighAir intake / turboSPN 1569 FMI 31Engine Protection — Power Derate ActiveEngine protectionSPN 627 FMI 2ECU Power Supply — Intermittent / ErraticElectrical / ECU powerSPN 639 FMI 2J1939 Data Link — Communication ErrorNetwork / J1939 datalink

Roadside first moves

Note the exact SPN/FMI and any companion codes, read the freeze-frame data, and don't keep driving a derated truck — it can escalate to a no-start. When in doubt, look up your code and get a qualified mobile diesel tech on the International A26.

FAQ

What are the most common International A26 faults?

The most common International A26 roadside faults are: DPF differential-pressure and failed-regen faults; DEF dosing and SCR conversion-efficiency faults; EGR valve / EGR cooler and boost faults.

Can a mobile mechanic work on a International A26 on the roadside?

Yes — most International A26 roadside issues are aftertreatment (DPF/DEF/SCR), EGR, boost, or electrical faults a mobile diesel tech can scan and often resolve on-site. Internal damage or a fully plugged DPF needs a shop.

What fault codes does a International A26 commonly throw?

Common heavy-duty SPN/FMI codes relevant to the International A26 include SPN 3251 FMI 2 (DPF Differential Pressure — Data Erratic); SPN 3361 FMI 7 (DEF Dosing Unit — Not Responding Properly); SPN 4364 FMI 18 (SCR Conversion Efficiency — Below Threshold); SPN 4094 FMI 31 (DEF Quality — Out of Spec). Look any of them up below.

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General repair guidance for the International International A26. Not a substitute for a scan-tool diagnosis on your specific truck.