Spareco Case Study Report: 17-6-14

Diesel Catalytic Converter
8 Feb 2016

Spareco Case Study Report: 17-6-14

The following report aims to establish the facts in relation to warranty claims on an aftermarket Diesel Particulate Filters (DPF), Part No. DPF003SC, supplied by (information redacted) to Mazda in (redacted) in April 2014, the vehicle and specified issues are outlined separately with their issues and suspected causes outlined in black text and the recommended course of action Spareco believes should have been performed at the time outlined in red text.

MAZDA 3 ((redacted) DEALER)

Car Details as given by (redacted) Mazda / (redacted): Mazda 3 2.0L Turbo Diesel

This vehicle was bought by (redacted) Mazda as a used car and was found to have a failed Diesel Particulate Filter. After attempting to clean the unit with degreaser and a pressure hose several times and refitting it to the car to obtain a forced regen, it was found that the “front of the DPF had melted”. (redacted) Mazda had not seen this vehicle before and had no service history on the vehicle.

Process recommendation:

• The history on this vehicle should have been checked for evidence of a reason for initial failure.

• The pressure/temperature sensors should have been checked before replacement of DPF.

When it was discovered that the original unit had melted down this should have raised flags for the dealer alerting them to an underlining issue.

• Further diagnosis and pre checks as outlined in DPF Fitment Guide for the Professional should have been completed before the DPF unit was replaced.

At this point a new silicone carbide unit was sourced by the Sales Department at (redacted) Mazda; it was purchased though the Parts Department and supplied to the Service Department for fitment.

“There were no fitting instructions attached to the unit just a part number and the contact details for (redacted) was the only things attached. We spoke to (redacted) about fitting and there was no mention about special circumstances around the DPF or things we should check”

The unit was fitted by Service, the oil and filter were changed, Engine Management Unit values were reset and there was a forced regen completed on the new Diesel Particulate filter without issue as per the Mazda replacement schedule. Both Sales and the Service Department test drove the vehicle with a combined distance of approximately 100km before the vehicle was put on a truck and taken to (redacted) Mazda for sale.

Process recommendation:

• There should have been attached to this unit the Warranty label as well as a copy of the DPF Fitment Guide for the Professional.

• When (redacted) Mazda spoke to (redacted) more info was required about correct fitting process including pre-checks and fitting guide should have been supplied.

MAZDA 3 ((redacted) DEALER)

Car Details as given by (redacted) Mazda / (redacted): Mazda 3 2.0L Turbo Diesel

While on test drive with a possible customer the vehicle was reported to lack power and during the test drive entered the Limp Mode bringing on the engine light. It was given to (redacted) Mazda Service Department for diagnosis and after some investigation it was found that the DPF was causing a restriction in power as well as having a higher than recommended pressure differential. A forced regen was performed however on road test the same issues were felt with restricted power and eventually the Limp Mode occurred again. The unit was removed as well as the injectors and inlet manifold for check and further diagnosis.

The injectors were checked by a local independent (redacted) Diesel Services and the following results were found.

1. Injector 1 was found to pass all tests (both return and delivery) with notes stating only a slightly higher than average specification fuel return.

2. Injector 2 was found to be the same as Injector 1

3. Injector 3 was found to have excessive return. Over a 1 minute return test with a maximum return of 30cc allowable an amount of 500cc approximately (the test was withdrawn at 30 seconds due to results) was found. A delivery test was not completed due to overwhelming return issue.

4. Injector 4 was found to have an acceptable return however its delivery was found to be only 59mm³ where a specification of 70mm³ is needed.

5. These tests were completed by a trained technician on a Bosch EPS200 series test bench using a Redat equipment update. (Denso Injectors).

All 4 injectors have since been replaced and the Engine Management System has been recoded to work with these calibrated injectors. Both the intake manifold and EGR were also removed however there were no reported issues with either. It should be noted that inlet manifold blockage is a common occurrence in these vehicles and that it can be extremely detrimental to the service life of a Diesel Particulate Filter.

The DPF was replaced with one borrowed from another used car and has since had no further issues with approximately 150km travelled.

Process recommendation:

• The history on this vehicle should have been checked for evidence of a reason for initial failure.

• These issues should have been picked up by the (redacted) Mazda Dealer as part of there pre-replacement process as outlined in the DPF Fitment Guide for the Professional


It is the opinion of Spareco that this vehicle was not diagnosed correctly in accordance with best practice DPF diagnosis and replacement. The following points summarise our thinking

1. The cars history was not sufficiently checked.

2. All recommended vehicle technical checks were not carried out.

3. Recommended DPF replacement process was not followed.

Other important notes:

• A new fitting kit should have been used.

• Engine sealant should not have been used to seal either end of the replacement DPF unit. (There was evidence of silicone sealant upstream of the particulate filter.)

• There are no recorded pressure differential readings from either Mazda Dealer even after failing 2 separate Diesel Particulate Filter’s. (OE and Zetti Emissions product)


Overview of Objectives:

A sample of ash has been supplied to an independent test facility for analysis to further understand the cause of failure in the supplied Diesel Particulate Filter DPF003SC, supplied by (information redacted) to Mazda in (redacted) in April 2014. See Picture 1 & 2 below.


Picture 1



Picture 2



Picture 3


Ash Test Results:

Understanding of the Test Graph (Refer Picture 3)

To understand the graph shown, the X line is Time, the Y-1 line is Weight and the Y-2 line is Temperature.

The test we perform consists of 77 minutes of increasing the temperature (Y-2 Blue) from room temperature to 400 degree’s. We then maintain a 400 degree temperature for 30 minute’s during this
time any raw diesel / oil contamination within the soot will burn off. Looking at the Green Y-1 line it starts from 100%, this will always start from 100% as the soot loaded equals this figure. This value
can only decrease as the test continues as the soot, raw diesel / oil is burning and decreasing the overall weight. The point stated on the green line is the final per-cent after the 30 minutes of 400 degree burn time, the per-cent shown at this point is the per-cent of soot left after the 400 degree burn time of 30 minutes. As stated previously any oil or raw diesel contamination within the soot will have burn off during this time. For example – the point shown on the graph states : 92.00 %, this means at a temperature of 400 degrees after 30 minutes the soot content now is 91.66 % from 100 % from the beginning of the test, so 100% – 91.66 % = 8.34 % , this 8.34% is burnt oil or raw diesel, so in a simple term the soot sample taken contains 8.34% oil or raw diesel contamination, the limit is 7.00 % ,
so the soot sample has failed our test as its over the 7% limit. In this term as we are over the 7% limit there is a problem with the car, whether it be over fuelling or leaking oil into the combustion chamber. As suggested in the attached case study several of this vehicles diesel fuel injectors did not pass OEM specification testes. 1 in particular was over 100% the required spec.

The next process in testing the soot sample is decreasing the temperature to 100 degrees, this is so we can cool the soot to a steady temperature, if we increase the temperature from 400 degree’s right after the previous 30 minutes there will be a chance we could burn the remaining soot too fast, once the temperature reaches 100 degree we hold the temperature their for 5 minutes forming our test base line.

We then increase the temperature to 700 degree’s and maintain this for duration of 9 minutes. The reason for doing this is to burn the remaining soot steadily leaving only a sample weight of other non
burnable contamination. You will notice there is a point at the end of this graph on the Green Y-1 line this is what’s left after the remaining soot is burnt. For example : the graph states 10.00%, this means 10.13% of foreign contaminate is left after the remaining soot has burnt, this will be due to engine component breaking up, for example piston rings slowly deteriorating or the burning of injector tips. The limit for this point on the graph is 2.00%, so again this has failed the test as it is over the 2.00% limit by 8.13%.

Conclusion Supplied by Independent Test Facility:

“After reading through the attached case study and completed a range of tests and examining the results we agree with the above mentioned study.. Our opinion after reading through this report is, the (redacted) Mazda Dealer purchased the vehicle with no evidence of any faults, once the faults were brought to there attention they only replaced the reported fault and no attention was made to any auxiliary components that could or indeed have caused the reported fault. The (redacted) Mazda Dealer took more attention to detail with their diagnostics and fault finding, but at this stage the DPF was already damaged, the correct procedures were taken to repair the vehicle however there has been no mention in the above document about the condition of the catalytic converter forward of the DPF unit (contained in the engine pipe) this is something that requires attention before replacement of
the DPF unit.”

Statement given by Independent Test Facility used to test DPF003SC.


Your email address will not be published. Required fields are marked *