DPF Outlet Temperature Too High

Detroit Diesel fault DD-3246-0 (SPN 3246 FMI 0) indicates: DPF Outlet Temperature Too High. It is a critical-severity fault and is commonly seen on DD13/DD15/DD16 engines in Freightliner and Western Star chassis.

It depends on severity. Critical and serious faults trigger derate or engine shutdown — do not continue driving. Moderate faults usually allow continued operation short-term but schedule repair to prevent cascading aftertreatment damage.

Estimated repair cost is $2,500-$6,500. Sensor/harness fixes fall at the low end; turbo actuator, injector, aftertreatment component, or head gasket repairs fall at the high end. Detroit DDDL software and sometimes factory parameter reset are required for proper reset.

California's heavy-duty OBD regulation requires the system to flag the PM filter before its filtering capability drops — from cracking, for instance — enough to push PM emissions past 0.07 g/bhp-hr, or past the applicable standard plus 0.06 g/bhp-hr, whichever is higher (Title 13 CCR 1971.1, section (e)(8.2.1)). Where no credible failure could reach that level, it must instead flag the case where no detectable filtering is happening at all. This threshold comes from the heavy-duty OBD regulation, which covers 2010 and later heavy-duty engines. If your engine is in a pickup at or under 14,000 lb GVWR it is certified under the separate medium-duty rule instead, so treat this as the design intent rather than your engine's exact limit.