PACCAR MX-11 SPN 3055 FMI 14 — DPF Condition (Parked Regeneration Required)

Code Details

Plain-English Meaning

The PACCAR MX-11 aftertreatment system manages DPF soot levels through passive regeneration during highway driving when exhaust temperatures are naturally elevated, and through active regeneration using the HC doser to raise DPF temperatures during driving when passive regen is insufficient. In applications that involve frequent city driving, heavy idling, short trips, or low-speed operation, exhaust temperatures may not reach the range needed for effective active regen during driving. When the DPF soot load accumulates to the level where the ACM determines that a stationary parked regen is required, it sets SPN 3055 FMI 14 and activates the driver notification. A parked regen on the MX-11 runs the engine at elevated idle in a stationary vehicle, maintaining high DPF temperatures long enough to oxidize the accumulated soot load. The truck remains operable after this fault is set, but a derate may be applied if the parked regen is not performed in a reasonable time.

SPN 3055 is Aftertreatment 1 Diesel Particulate Filter Condition; FMI 14 is a condition-exists flag indicating the DPF soot load has crossed the parked regen request threshold. On the PACCAR MX-11, the aftertreatment control module tracks DPF soot load through differential pressure measurement across the filter. When the calculated soot load reaches the parked regen threshold, SPN 3055 FMI 14 is set and the driver warning system activates. PACCAR ESA provides real-time DPF soot load data, regen history records, and regen inhibit status information. ESA can initiate a service-level parked regen to monitor the cycle completion and confirm soot load reduction. The ESA regen inhibit list shows which operating conditions are currently preventing a regen from running, which is useful for troubleshooting interrupted or incomplete parked regen cycles.

Common Symptoms

• DPF regeneration required lamp or warning message on the driver display
• Engine derate or speed limitation if the parked regen request has been delayed
• Reduced performance during heavy-load or low-speed operation
• Elevated idle speed during an in-progress parked regen cycle

Possible Causes

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

• Low-speed or city driving duty cycle preventing driving regen from completing
• Extended idling periods that accumulate soot without allowing regen temperatures to be reached
• Repeated driver-initiated interruptions of driving regen cycles
• Short-trip operation where exhaust temperatures do not reach driving regen conditions
• HC doser fault preventing active regens from running correctly

First Checks

• Perform a parked regen following the driver display prompts with the vehicle stationary outdoors in a safe area with the parking brake fully engaged
• Connect PACCAR ESA to monitor DPF soot load before and during the parked regen to confirm the cycle is progressing and soot load is decreasing
• If the parked regen does not start or complete, check ESA for active inhibit conditions such as low fuel, coolant temperature out of range, or an HC doser fault code
• Review the regen history in ESA to determine whether driving regens have been consistently failing to complete, which may indicate a regen system fault beyond normal duty cycle effects
• Discuss application duty cycle with the operator — if most operation is urban or short-trip, proactive parked regen scheduling may be needed to prevent recurring DPF soot overloading

Can I Keep Driving?

The truck is driveable when SPN 3055 FMI 14 first sets but may have a moderate power or speed limitation. Complete the parked regen as soon as safely possible to prevent the soot load from escalating to a level that triggers more severe derating.

Related Lookup Pages

• FMI 14 explanation
• Aftertreatment fault codes
• Search this code