Why Does My DPF Keep Blocking?
Recurring DPF warnings usually deserve more investigation than simply cleaning the filter again. Here are the common reasons a DPF can load repeatedly.
Cleaning can restore a serviceable filter, but if the vehicle is producing excessive soot, failing to reach regeneration conditions or receiving incorrect sensor information, the DPF may load again.
Common Reasons a DPF Keeps Blocking
Driving & Duty Cycle
Short trips, stop-start operation and low exhaust temperature can reduce opportunities for successful regeneration.
Sensor or Regeneration Fault
Pressure and temperature sensing faults can interfere with the system's ability to calculate loading or complete regeneration.
Engine or Emissions Problem
EGR, boost, fuelling, oil consumption or operating-temperature issues can contribute to excessive soot or repeated loading.
Soot Loading vs Ash Loading
Soot is combustible and can be reduced during successful regeneration under the right conditions. Ash is non-combustible residue that accumulates over time and is not removed by regeneration. High-kilometre filters can therefore become restricted even when regeneration is operating normally.
From Our Workshop
Off-car DPF cleaning in our Carrum Downs workshop.
Purpose-built cleaning equipment used in our workshop.
Commercial-vehicle DPF cleaning carried out in-house.
How We Approach the Job
How quickly did the warning return and what work was done last time?
Check regeneration history, pressure information and relevant engine data.
Determine whether restriction, ash or physical condition is contributing.
Address the contributing issue and clean the filter where appropriate.
Related DPF Services & Guides
Frequently Asked Questions
Why does my DPF keep blocking after it has been cleaned?
A recurring blockage can indicate that the underlying cause was not resolved, such as driving conditions, failed regeneration, sensor faults, EGR, boost, fuelling, oil contamination or operating-temperature problems.
Can short trips block a DPF?
Repeated short-trip and stop-start use can reduce the opportunities for the exhaust to reach conditions required for successful regeneration.
Does regeneration remove ash?
No. Regeneration is intended to reduce soot. Ash accumulates over the life of the filter and requires a different cleaning approach when it becomes excessive.
Should I keep paying for repeated cleans?
If the filter keeps loading, diagnosis of the underlying cause is more useful than repeating the same cleaning process without understanding why the issue returned.
DPF Keeps Blocking?
Book diagnosis so we can work out what is causing the repeated loading.
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