International A26 SPN 3246 FMI 0 — DPF Outlet Temperature Very High

Code Details

Plain-English Meaning

The International A26 aftertreatment system monitors exhaust gas temperature at the outlet of the diesel particulate filter using a dedicated temperature sensor. Under normal operating conditions, the DPF outlet temperature rises during an active regen event as accumulated soot is oxidized and then returns to the normal exhaust temperature range when the cycle completes. When SPN 3246 FMI 0 is logged, the outlet temperature has exceeded the critical high threshold defined in the A26 ECM calibration. This threshold is set at a level that indicates an abnormal thermal event rather than a normal peak regen temperature. The most common cause on the A26 is a hydrocarbon dosing injector that does not shut off cleanly when commanded, continuing to deliver unmetered fuel into the exhaust and DOC where it oxidizes and drives DPF outlet temperatures above the limit. Internal injector leakage and high soot loads are also possible contributors. The ECM response is to inhibit further regen activity and may impose an engine derate.

SPN 3246 is Aftertreatment 1 Diesel Particulate Filter Outlet Gas Temperature; FMI 0 indicates valid data above the normal operational range at the highest severity level. On the A26 engine (GHG17 emissions), the aftertreatment system uses multiple temperature measurement points to manage regen cycles and detect over-temperature events. International Servicemaxx provides access to live aftertreatment temperature data across all sensor positions and stores freeze-frame data at the time of fault detection. The Servicemaxx hydrocarbon dosing injector actuation test confirms whether the injector responds correctly to open and close commands. Cross-referencing the DPF outlet temperature reading with DPF inlet and DOC outlet readings during the freeze-frame can indicate whether the over-temperature is localized to the DPF outlet region or represents a broader thermal event in the aftertreatment assembly.

Common Symptoms

• Check engine and aftertreatment warning lamps illuminated
• Engine derate or speed limitation active
• Active regen inhibited or prevented by the ECM
• Exhaust odor of raw or partially combusted fuel
• Elevated DPF differential pressure if soot loading was also elevated at fault set

Possible Causes

Possible causes may include the items below. The list is not a parts diagnosis.

• Hydrocarbon dosing injector stuck open or not seating correctly when commanded off
• Fuel injector internal leak on one or more cylinders contributing unburned fuel to the exhaust
• Extremely high DPF soot load causing an extended regen with abnormal peak temperature
• DPF outlet temperature sensor failed or reading out of range
• Engine oil consumption contributing excess hydrocarbon load in the exhaust stream

First Checks

• Connect International Servicemaxx and read the freeze-frame data for SPN 3246 FMI 0 to determine the temperature peak value and the state of other aftertreatment parameters at fault set
• View live aftertreatment temperature sensor data to compare DPF outlet readings against DOC inlet, DPF inlet, and SCR inlet values under steady-state conditions
• Perform the Servicemaxx hydrocarbon dosing injector actuation test to confirm the injector opens and closes on command without continuing to deliver fuel when commanded off
• Review cylinder balance and injector contribution data to identify any cylinder showing abnormal fuel delivery that could indicate an internal injector leak
• Inspect the physical DPF for thermal damage signs — discoloration beyond normal soot patterns or elevated backpressure after a completed regen may indicate substrate damage

Can I Keep Driving?

The engine derate may be significant. Do not force a parked regen while this fault is active — the underlying hydrocarbon source must be identified and corrected first to prevent further damage to the DPF substrate and SCR catalyst.

Related Lookup Pages

• FMI 0 explanation
• Aftertreatment fault codes
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