DPF (Diesel particulate filter) - Part 2

Common causes of DPF blockage

The main cause of blockage soot particle filters (DPFs) are frequent short-circuits where no regeneration conditions are reached. Therefore, it is not advisable to equip DPF with vehicles used for urban routes.

Continuous driving with a lit DPF signal light and without successful regeneration results in excessive soot deposition in the DPF, up to 95 percent charge. Then regeneration is no longer possible and DPF replacement is required.

Often the error does not only apply to the DPF, but to the entire exhaust system - faulty temperature sensor, faulty temperature sensors, additional system components (if applicable), poor connections, installation problems.

Question 1:
The heater warning light flashes. Why? What to do?

Answer 1:
DPF regeneration is not completed during normal driving and DPF has reached maximum saturation, which can still be regenerated. The limit value depends on the model and year of manufacture, but the range is 105 to 125 percent. Possible causes are frequent short distances - large soot deposition, and DPF regeneration does not take place, because the necessary conditions are not met. Frequent interrupted regenerations, e.g. when the engine shuts down during regeneration. It is valid for short-distance drivers who have met the conditions required to activate regeneration. If the light does not stop flashing in the conditions of faster driving on an open road, it is necessary to go to the service.

Question 2:
Under what conditions is the regeneration process interrupted?

Answer 2:
The regeneration process is interrupted after it is successfully completed, or:
a) after the maximum regeneration time (20-25 min)
b)     if the engine shuts down or runs at lower power
c)     if the engine is idling for a long time (5-10 min)
d)     if the exhaust temperature sensor detects 1000 ° C
e)     if an error occurs during regeneration related to any of the components relevant to combustion (suction / injection system)
If regeneration is interrupted after it has started but before reaching 50%, the heater warning light flashes the next time the engine is started (cold and warm) and regeneration resumes after the conditions are met.

Question 3:
How long does complete regeneration take?
a)     In best case
b) in the worst case

Answer 3:
a)     During constant conditions, e.g. the exhaust gas temperature required for regeneration is always above the required value, during highway / open road journeys, the average regeneration time is 10 minutes.
b)     Driving downhill, frequent low-load driving (city driving, idling), allow the exhaust temperature to drop. If the conditions for activating regeneration are fulfilled, active regeneration can take up to 25 minutes (depending on the type of engine). If complete regeneration is not possible during this period, it will be interrupted.

Question 4:
How does regeneration affect oil life?

Answer 4:
During each regeneration or regeneration attempt, a certain amount of fuel is injected into the engine, which shortens the life of the oil. If the INSP inscription appears on the instrument panel, the engine oil has run out and needs to be changed. Failure to do so may result in engine damage.

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