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Bosch: Choose the Right Injector, Why Injectors Fail

Why Injectors Fail

Bosch Choose the Right Injector. (n.d.). Retrieved from

The common rail system is a major advancement in diesel technology.

This system provides diesel engines with:

  • Quieter performance

  • Improved fuel economy

  • Higher torque

  • Lower emissions

The key causes of injector failure are:


Poor Fuel Filtration

A common problem with diesel injectors is erosion of the control valve. The heart of the common rail injector is the valve through which fuel passes at extremely high pressure. The passage opening is sealed using a pressurized ball that is only 1mm in size. A proper seal is critical for exact injector performance. Abrasive contaminants, released by inadequate filtration, can erode and damage the control valve and not allowing the ball to seal.

This can lead to:

  • Excessive smoke

  • Starting or idling problems

  • Potential engine failure

What Can I Do?

To ensure exact performance within the designed service life of the injector, use only OE filters or filters having the same OE micron rating and follow the recommended OE filter change interval. Using anything less can cost you more in the long run.

Fuel Contamination

The majority of diesel engine problems stem from contaminated fuel.

Common problems include:

Corrosion from excessive water in the fuel.

Two ways water can get into the fuel:

  • Through the delivery system

  • Through the tank vent

  • Micro fine particles in the fuel

  • Improper fuel storage, which is caused by water in the fuel

What Can I Do?

Always purchase fuel from a reputable service provider and use a proper fuel/water separator. Periodic inspection of the vehicle’s tank vent is also recommended.

Incorrect Installation

Missing sealing rings, incorrect tightening torque, incorrect cleaning of the nozzel can cause:

  • Poor performance

  • Misfiring

  • Black smoke

  • Check engine light (MIL) to come on

What Can I Do?

Always follow the engine manufacturer’s maintenance procedures and have repair work done by a reputable shop.

Non-OEM Approved

Re-manufactured Products

Not all re-manufactured injectors are the same. The quality of any re-manufactured injector depends on the re-manufacturing process and components. Some manufacturers sell refurbished/used injectors and market them as rebuilt. However, instead of being rebuilt, they are merely cleaned and polished, and the tips are not replaced. You might get a great deal on these non-OEM approved products, but you are taking a huge risk that these injectors may not be better than the one you are trying to replace.

What Can I Do?

Make sure your car is being serviced by a reputable shop and ask about the parts they use on your diesel engine to ensure they are from an OEM approved supplier.

Bosch’s re-manufactured injectors are exactly the same as OE injectors in design, engineering, materials, manufacturing and quality control. Bosch re-manufactured injectors include all OE updates, so they can often be superior to the OE injectors that they replace.

If you are purchasing your own injectors, you should purchase from a reputable, OE endorsed manufacturer.

If considering injectors from a non-OE endorsed manufacturer, be sure to ask the following questions to determine if the cost savings is worth the risk:

  • Do these injectors use new or reconditioned components?

  • It is preferred that the re-manufactured injector use all new high-wear components vs. salvaged components.

  • How are the re-manufactured injectors tested?

  • You want injectors that are tested to exact OE test specifications and not reverse engineered specifications.

  • What type of testing equipment is used?

  • It is preferable that their testing equipment is certified by the OEM.

  • The test equipment should not be something they build themselves.

  • It should be traceable back to a standard.

  • Is there a warranty?

  • Many reputable manufacturers offer at least a one-year warranty.

  • Are the remanufactured/rebuilt injectors upgraded to meet new OE specs

  • Are component improvements added to match changes made by the engine manufacturers?

Bosch is the world’s leading supplier of diesel fuel injection systems and is standard equipment on many diesel engines today. You can be confident when you install Bosch new OE injectors for the aftermarket, Bosch re-manufactured injectors, or Bosch-authorized rebuilt injectors.

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