With more diesel-powered cars and light commercials on the road there is a greater need for repairers to service and repair them.
Early Diesel Particulate Filter (DPF) fitted vehicles are becoming older, so repairs are becoming more common and costs may be high, relative to the value of the vehicle.
Correct Diagnosis Is The Key To A Successful Repair
One initial indicator of the DPF’s condition is to look for soot in the tailpipe. Soot would indicate that the DPF’s core is damaged and so, no longer an effective filter.
Obviously, further diagnosis by scan tool is essential and even removal for a physical examination is highly recommended. If removed, use a bore scope to examine the back end of the ceramic core, and look for signs of crumbling, cracks or melting.
Also look for stains on the back surface of the DPF core. As staining – either black or white indicates some form of internal damage due to excessive heat, incorrect crankcase oil or the use of an incompatible fuel additive. If the back of the ceramic is either a pristine white or light grey, then the DPF’s core may be intact. The cause of the DPF failure needs rectified before the DPF is repaired or replaced.
Remember the DPF failure is the symptom, not the problem!
Check List Of The Most Common Faults:
- Continuous urban drive cycles
- Incorrect engine operating temperature – too cold
- Incorrect or contaminated lubricating oil – must be the correct “low solids” DPF oil
- Incorrect or contaminated fuel – Fuel additives, bio diesel
- Induction and intercooler system air leaks – check for split hoses and loose clamps
- Blocked or split pressure sensor pipes and hoses
- Faulty DPF temperature pressure sensors or pressure differential switch/sensors
- Glow plugs – any faulty plugs too rich cold starting
- Mass Air Sensor – faulty
- Internal DPF filter cracks
- Faulty, damaged, poor quality or a poor quality hi-flow catalytic converter
- EGR valve stuck or failed
- Turbo failure, leaking turbo oil seals
- Injectors leaking, stuck open or not calibrated.
Your DPF Options – Pros And Cons
If the DPF is structurally OK and is only blocked, then cleaning may be an option:
- On car aerosol DPF cleaning may work in minor soot blockages but can’t fix structural damage, nor can it clean a DPF that is filled to capacity with ash. It isn’t possible to move particulate matter through a DPF’s ceramic core!
- Off-car cleaning is an option where there is no damage to the DPF core. A two to three day turn-around time can be an issue
- A good quality new after-market DPF can be a more economical option, costing from between $800 and $1500, while still meeting OE performance in the areas of filtration efficiency, holding capacity, flow rates, temperature resistance and service life
When the internal structure of the DPF has been damaged by overheating or other problems then the DPF must be replaced:
- The removal or modification of the DPF or cat is not an option as it is illegal in all states, with fines in NSW, for example, of up to $11,000 for an individual or up to $22,000 for a company
- Although a genuine OE replacement DPF is certainly a good option it can be very expensive with prices commonly ranging from $2500 to $14000 plus!
- Second hand DPFs can cost $1,000 and their condition is unknown. Most importantly, it’s impossibleto reset the vehicles ECU properly during the install, as it can only be reset to start from “0” for a new DPF installation and cannot be set to suit a used, partially filled second hand DPF. This will potentially cause ongoing error codes and issues
- Again, a good quality after-market DPF can be a more economical option, costing from between $800 and $1500 and meeting OE performance in the areas of filtration efficiency, holding capacity, flow rates, temperature resistance and service life. They are a fast and direct bolt-on replacement for the OE DPF and usually include new gaskets, washers, nuts etc. Generally, a warranty comparable or better than with an OE unit is provided.
Charles Anderson is the Director of DPF Australia, Australia’s only after-market DPF specialists.