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Main causes of damage in Common rail injectors - AutoNorma

Main causes of damage in Common rail injectors

Common Rail injectors  are very popular today. They are used not only for diesel engines, but also for gas engines. In modern diesel engines, great emphasis is placed on achieving the best performance while reducing fuel consumption and harmful emissions. High demands were placed on injection systems. Injection pressures of around 2000 bar are now standard and therefore their work must be very precise. But what causes damage to this system?

Low fuel quality

Whether they are injectors from Bosch, Delphi, Denso or Siemens VDO / Continental VDO, they all have in common that they work under pressure of more than 2000 bars. The components used in production have variations in size of several microns and are therefore very susceptible to the flow of quality fuel that lubricates them.
All impurities, solid particles, and water in diesel fuel damage these precision injector elements. They damage the injector surface by erosion and corrosion. Paraffin crystallizing in poor quality fuel can also lead to an injection system failure. Simply put, the injectors will clog. Thus, fuel quality is crucial in terms of durability of the injectors and the injection system as a whole.

Nízká kvalita paliva

The fuel filter is clogged

The fuel filter is designed not only to trap and store all particulate contaminants in form of solid particles, but also to separate water from the fuel, thereby preventing corrosion of the individual parts of the injection system. Extending the filter change intervals and using low-quality filters that are not intended for your car model can cause damage to the injectors. 

Palivový filtr je zanesený

Contamination in the system

Any foreign objects entering the system may damage the injectors. Parts of rust, dust penetrating through leaking joints, small metal debris, water or other unwanted liquids, or a damaged fuel tank may all cause malfunction of injectors (or injection pump). 

High-pressure pump

Sometimes the feed pump or the high-pressure pump itself (how we remanufacture the common-rail pumps) starts to form small metal shavings, which then reach the injectors through the dividing slat and irreparably damaging them.

Vysokotlaké čerpadlo

Poorly executed chiptuning

Any amateur attempt to increase performance, EGR valve interruption (prolink do EGR), or other unwanted or improper intervention, may result in injector damage.


Diagnosis and repair of injectors

Injector damage is accompanied by characteristic indications. One of the basic injector tests is the overflow test. If the indications listed below appear in your vehicle, it is possible that the problem may be in a faulty injector:

  • difficult cold start
  • decrease in vehicle performance
  • black smoke
  • jerking or burning failures while driving
  • characteristic "knocking" of injectors
  • engine overheating
  • irregular idling
  • increased fuel consumption
  • sudden engine stop

In the event of a leak in the injection system, too much fuel enters the cylinder at the tip of the injector causing an increase in the combustion temperature and dilution of the oil film.
This may damage the piston, cylinder, head, turbocharger, catalytic converter, or particulate filter (DPF, FAP).

High amount of fuel injected causing clogging of particulate filter (DPF cleaning) or EGR valve (how we remanufacture EGR)

zanesený DPF
Zanesený DPF

Do not overlook the aforementioned indications as using a car with inoperative injectors can lead to a complete engine failure. You can find out more about this problematic in the "how to repair the injectors" section.