Field Remedy: 2128

Subject: Diesel-particle filter (DPF) - Question and Answer

Models:
All 2004...

Complaint: Different Diesel-particle filter (DPF) occurences.

Cause: Process characteristic DPF and mode of operation.

Production: .

Remedy:
Important: In case of complaint, please follow TSB/Field Remedy
database, in particular TSB 1976, 2043, 2054, 2260.

Question 1: Has the ECU supplied black box data to give information on the last regeneration or regeneration sequence?

Answer: All applications show the current loading status in percent, and the distance covered since the last regeneration or regeneration attempt. TECH 2 gives no information on whether the previous regeneration (or regenerations) were complete and successful.

Question 2: The glow plug symbol is flashing. Why? What should be done?

Answer: The DPF regeneration has not been completed during normal driving and has now reached its maximum saturation at which it can still be regenerated. The limit value depends on variant and MY, but is in the range of 105% - 125%.
Possible causes for this are:
a.) Frequent short distance journeys, i.e. high soot loading while at the same time regeneration of the DPF does not take place because the conditions necessary were not fulfilled.
b.) Frequent interrupted regenerations, i.e. the engine was switched off during regeneration. Applies to short journey drivers who have at least fulfilled the conditions for triggering regeneration.

If the glow plug light flashes, the vehicle should be driven until it goes out.

Important: Regeneration is carried out more often (2 - 3 times) during the first 1000 km of driving in order to achieve a defined loading status of the DPF. This is necessary to reduce component and system tolerances, and forms the basis for precise calculation of the soot loading in the DPF.

Question 3: What conditions are required for the DPF to begin regeneration?

Answer: The following conditions must be fulfilled for regeneration to begin.
a.) Engine running since start > 2 minutes.
b.) Calculated saturation > 80%.
c.) Coolant temperature > 70C for at least 2 minutes.
d.) No DPF-relevant faults stored in system.
e.) A defined vehicle speed threshold must be exceeded in some cases
(e.g. for 80%-100% loading, one time 100 km/h), at loadings above
100% the speed does not matter.

Question 4: After service regeneration, TECH2 data list shows a current loading status of 70% or 78%. Why?

Answer: The regeneration intensity of the static regeneration is not as effective as that of dynamic regeneration. The value is therefore set to 70% - 78% loading so that the ECU then triggers a dynamic regeneration when the required conditions (see question 3) are fulfilled.
Exception: Vehicles equipped with 1,7 liter Diesel engine will show
a saturation level of 32% after service regeneration.

Question 5: Under what conditions is regeneration interrupted/ended once it has started?

Answer: Normally when regeneration has been successfully completed, or:
a.) After a maximum regeneration time (20 - 25 min.).
b.) If the engine is switched off or has stalled.
c.) If the engine is left idling for a long time (5 - 10 min.).
d.) If 1000C is detected by the exhaust temperature sensor.
e.) If during regeneration, a fault is detected on the components relevant for combustion (injection/intake system).
If a regeneration is interrupted once started but before it has been 50% completed, the glow plug lamp flashes on the next engine start (cold or hot) and regeneration begins again once the operating conditions (see 3) have been fulfilled.

Question 6: The DPF loading is (far) below the threshold value for the flashing glow plug lamp, but the customer comes in with the SVS light on and the DPF clogged. Why?

Answer: In this case, there is very likely a hardware fault or tuning. This fault is usually due to a leak in the air-carrying parts. Often there is a split in one of the charge air hoses or charge air cooler.
Due to the leak, which the ECU or loading model does not detect, the engine will emit more smoke if the pressure difference remains below a defined threshold. The increased smoke emission can clog the DPF.
Furthermore, a disproportionately high loading of the DPF can be due to a (partly) open EGR valve.
A tuned engine emits more smoke than calculated in the soot loading model. This may result in a clogged DPF without any customer notification.

In general please check the field remedy database for known fault pictures and diagnosis instructions.

Question 7: How long does complete regeneration take?
a.) In the most favourable case?
b.) In the least favourable case?

Answer: a.) Under constant conditions, i.e. the exhaust temperature necessary for regeneration always lies above the required value, for example during motorway/cross-country driving, the average regeneration time is 10 minutes.
b.) Vehicle conditions such as long down-hill descents, frequent driving in the low-load range (city driving, idling) allow the exhaust temperature to fall. If the conditions for triggering regeneration were fulfilled, the active regeneration time can be extended up to 25 minutes (depending on engine type). If complete regeneration is not possible within this period, the regeneration will be interrupted.

Question 8: How does regeneration affect the oil life?

Answer: On each regeneration or attempted regeneration, a certain diesel fuel amount is injected into the engine oil which reduces the oil life. If the "INSP" light in the instrument cluster comes on, the engine oil is exhausted and must be changed. Failure to do so could damage the engine.

Question 9: Is the DPF sensor important for the regeneration procedure?

Answer: The sensor does not initiate the regeneration, which is based on a model. The DPF sensor fulfils purely a diagnostic function to monitor the counter-pressure in the DPF.
Exceptions are the Antara, Captiva, Z20DTx; on these models, the DPF sensor is involved in triggering the regeneration. Question 10: How does the Soot loading value in ECU behave?

a.) After SPS programming.
b.) After a change of ECU.
c.) After disconnecting the battery.
a.) After a pure SPS, the loading status is retained. On a change of
ECU or reprogramming of the existing ECU, after reset the loading
status jumps to 104% (e.g. on the Z19DTx), and then regeneration takes
place. Variations are possible depending on model year or application.
b.) The current soot loading value will be stored on Tech 2 flashcard
prior ECU removal. This value will be programmed into new Service ECU
via ECU reprogramming. c.) No effect.