A diesel particulate filter is part of your truck’s aftertreatment system, designed to capture and store particulate matter (mainly soot) produced during combustion. The DPF prevents these pollutants from being released into the air, ensuring your vehicle complies with strict EPA emission standards.
But here’s the catch: DPFs aren’t self-cleaning by default. Over time, soot accumulates in the filter, which needs to be burned off through a process called regeneration. If this process is disrupted or ignored, DPF problems begin to stack up—and fast.
This is, by far, the most common cause of DPF failure. When a truck doesn’t reach the proper temperature for passive regeneration, soot doesn’t fully burn off. This is typical in trucks that idle too long or make frequent short trips—conditions that don’t allow the exhaust system to get hot enough.
In cases like these, active regeneration—controlled by the truck’s ECM—must kick in. If sensors or components involved in this process fail, forced regeneration at a repair facility may be the only solution.
DPF systems rely heavily on input from pressure and temperature sensors to determine when a regeneration cycle should occur. Faulty readings can delay necessary regens or trigger false alerts, contributing to filter overload.
Engines burning oil often push ash through the combustion cycle, which settles in the DPF. Unlike soot, ash cannot be burned off during regeneration. Instead, it builds up inside the filter and clogs it. Ash buildup typically requires professional cleaning or full-on DPF replacement.
Low-grade diesel or contaminated fuel can lead to incomplete combustion, producing more soot than usual. The DPF clogs up faster, and the need for regeneration becomes more frequent and aggressive, stressing the system.
Failures in your exhaust gas recirculation (EGR) or turbo system can raise combustion temperatures or inject unburned fuel into the exhaust stream. Both conditions increase soot output and make your DPF work overtime.
Catching DPF issues early can prevent more expensive repairs down the road. Here are the most common symptoms to look for:
When passive and active regens fail, the next step is a forced regen. This procedure uses a scan tool to override the ECM and raise the exhaust temperature high enough to burn off trapped soot.
This fix is effective but temporary if the root cause—like a failed sensor or poor combustion—isn’t addressed.
For filters packed with ash or soot, professional DPF cleaning is necessary. There are two common methods:
A well-maintained DPF can often be cleaned multiple times before replacement is needed.
If diagnostics point to a failed temperature sensor, differential pressure sensor, or EGR valve, replacing these components is vital to prevent repeat DPF failures. Also, don’t overlook turbochargers or fuel injectors. They can impact combustion efficiency and increase soot production.
Sometimes, software glitches or outdated calibration files in the ECM can interfere with regen timing. Updating or reprogramming the ECM can resolve these issues and help the DPF function more efficiently.
Routine inspection and preventive maintenance are your best tools for avoiding DPF issues. Here’s what to prioritize:
For fleet owners and drivers operating in and around Phoenix, AZ, the desert heat introduces a unique set of challenges. High ambient temperatures can interfere with regeneration timing, while dust and debris increase the likelihood of DPF clogging. Add in long-haul desert routes with limited idle time, and you’ve got an environment that demands rigorous attention to aftertreatment systems.
If you need mobile DPF and aftertreatment system repairs in Phoenix, AZ, reach out to our team at Onsite Truck & Equipment Repair today. Take action, get it diagnosed, and keep your rig running clean and efficient.
