The mysterious DPF!
Is your Diesel Particulate Filter (DPF) clogged? Is your vehicle running in limp mode, lacking in power, or is the engine unable to start?
Does your vehicle struggle to accelerate from traffic lights? Is the engine warning light on? Do you have AN AdBlue malfunction?
At OGS Mechanics, we can help.
By treating the early symptoms of Diesel Particulate failure, you can avoid expensive unnecessary repairs. OGS Mechanics can help in the efficient diagnosis of this fault – restoring your vehicle’s performance and extending the life of your vehicle’s DPF. At OGS Mechanics, we specialise in diagnosing DPF faults and assisting vehicles that are running with a lack of power – our highly trained technicians use advanced diagnostics equipment. Our diagnostic procedure includes:
- scanning control units for faults
- running test and reading relevant live data, comparing against specification
- checking software level of relevant ECUs
Upon gathering all data, a test plans will follow to identify the exact cause of the DPF problems.
Correctly diagnosing a DPF fault / an engine running with a lack of power is essential to avoid replacing unnecessary parts – something that could create significant and unnecessary high cost.
From 1992 new cars and vans had to meet defined Euro emissions standards when being built as part of a global initiative to improve air quality by reducing emissions.
‘Euro 6’ is the latest directive set to help reduce the level of harmful pollutants produced by vehicles and since September 2015, all new cars and vans have had to be built to meet the Euro 6 emission standard. Diesel Particulate Filters were installed on vehicle exhaust systems to meet Euro 5 emission regulations.
While DPFs are a very important element in reducing exhaust emissions. they also are an added source of problems and expense. They can often cause vehicles to slip into emergency limp mode (more precisely, reduced power mode if the maintenance cycle known as ‘regeneration’, which is controlled by the engine’s ECU, is failing to complete several times causing the filter to become clogged.
Understanding the Diesel Particulate Filter and its functionality
How does the DPF work?
The DPF looks similar to an exhaust silencer box but is mounted close to the engine, usually within the same housing as the catalytic converter. Inside is a complex honeycomb ceramic structure designed to filter exhaust gases while minimising flow reduction (which would otherwise limit performance).
By forcing the exhaust gases through the walls between the channels of the DPF, the particulate matter is deposited on the walls, reducing the amount of air pollution. Once the DPF reaches a certain level of ‘Saturation’ it performs a regeneration cycle which burns off the particulate matter retained inside the filter.
In normal driving conditions, a DPF should run for approximately 100,000 miles without the need for forced maintenance.
DPFs can and will fail most of time prematurely through no fault of their own. If a DPF has blocked prematurely due to a fault further upstream, then simply replacing or cleaning the filter will not solve the problem and the DPF will usually block again after just a few miles.
To have a DPF block again after just a few miles after cleaning or replacing indicates that there is a fault within the engine management system that is preventing successful DPF regeneration cycles from being completed. A comprehensive diagnostic check can reveal the DPF regeneration cycle history within the engine ECU memory.
It is important that the cause of DPF failure is identified and repaired. Reasons for DPF failure include:
- Combustion/compression issue;
- Exhaust Gas Recirculation (EGR) system problem;
- Injector over-fueling;
- Faulty glow plugs or glow plug control unit;
- Air intake issues;
- Turbocharger problem;
- Faulty thermostat;
- Incorrect software version.
Here is a list of the most common generic DPF fault codes:
- P1471 Diesel particulate filter (bank 1) regeneration not completed;
- P2002 Diesel particulate filter (bank 1) efficiency below the threshold;
- P2003 Diesel particulate filter (bank 1) particulate mass too high;
- P242F Diesel particulate filter (bank 1) regeneration not active;
- P244A Particulate filter differential pressure too low;
- P224B Particulate filter differential pressure too high;
- P2452 Particulate filter differential pressure sensor malfunction;
- P2453 Diesel particulate filter differential pressure – sensor malfunction;
- P2454 Diesel particulate filter differential pressure – sensor voltage too low;
- P2455 Diesel particulate filter differential pressure – sensor malfunction;
- P2458 Particulate filter regeneration maximum regeneration time exceeded;
- P2459 Particulate filter regeneration, regeneration frequency implausible.
For a regeneration to take place there must be a sufficient amount of fuel in the tank – roughly at least quarter of a tank – and the soot content must be under 45% on average.
If many regeneration cycles are enabled but not completed successfully, engine oil can become diluted and/or degraded with diesel and if the vehicle is equipped with oil quality monitors, then passive regeneration will also prohibited until the quality monitor is reset via the diagnostics machine. It is advised that oil and the oil filter are replaced before any forced regeneration.
Passive regeneration vs. forced regeneration? What’s the difference?
Passive regeneration is when the regeneration process is initiated by the engine ECU whenever required. Forced regeneration is the process initiated by technician via a diagnostic machine when a DPF is too clogged for passive regeneration to happen. Forced regeneration can be completed stationary or in motion depending on the vehicle software.
Contact OGS Mechanics today if your car or van has restricted performance, or any engine management warning light on and we’ll be able to assist with diagnostics and restoration of the vehicle’s performance.