11 April 2016
The number of vehicles fitted with Diesel Particulate Filters (DPF) in Australia is growing fast. As a result, mechanical workshops and automotive services centres are reporting an increase in the number of customers presenting with DPF Warning lights on the dash.
“It is becoming more important for automotive mechanics to arm themselves with the skills to be able to accurately diagnose DPF faults and take the appropriate action,” said Ross Lamb, Sales & Marketing General Manager, for Ryco Filters. “Making the right diagnosis the first time can save your customers the expense of replacing these costly items.”
Firstly, it is important to understand how a DPF works. “The DPF acts as a soot trap that collects particulates from the exhaust emissions,” explained Ross. “The exhaust gasses escape through the porous media walls, while particulate matter is trapped within the DPF.” The DPF self-cleans during a process called “regeneration” whereby the ECU will add in extra fuel to generate temperatures inside the DPF to 600° C (and higher) in order to burn particulates into ash which is then expelled through the exhaust.
There are a number of reasons that a DPF can fail besides blocking up over its service life.
“The most common reason for the failure of a DPF is that it has become blocked enough to impact on the engines performance. Do not assume that age has caused the failure and that simply replacing the DPF will cure the issue. “Always ensure that the root cause of the failure is thoroughly investigated and correctly identified, it may save the customer from having an expensive part needlessly replaced,” added Ross. There are also a number of reasons why a DPF may have failed prematurely. This includes the use of incorrect engine oil, a faulty ERG valve, turbo charger faults and damaged pressure lines or sensors, and driving style.
“Stop, start city driving is to DPF’s what Kryptonite is to Superman,” quipped Ross. “The issue that in these driving conditions, the DPF may never reach that critical temperature of 600°c at which point regeneration occurs. As a result the DPF blocks up faster bringing on the warning light earlier and at worst cast a no start situation.”
It is important that a thorough fault diagnosis be carried out by a fully trained technician with appropriate diagnostic equipment to establish if the DPF needs to be replaced. Any unrectified upstream faults will result in the replacement DPF failing prematurely.
“Fact finding is critical to ensure accurate DPF fault diagnosis,” said Ross. “In addition to establishing if there is a fault occurring elsewhere on the vehicle it is important to quiz the owner about their driving habits, ask them how long the DPF warning light has been on and well as confirming if the oil has been changed recently or if an additive was used. “The answers to these will allow you to make a much more accurate diagnosis and if possible avoid DPF replacement or premature failure of a replacement DPF,” Ross added.
The Ryco DPF range is available nationally from leading Ryco distributors from mid April.