EGR Valves & Emissions
EGR Valves & Emissions

EGR Valves & Emissions

Over the last 10 years, the increasing focus on emissions has challenged the automotive industry and forced it to optimise and create more output from ever smaller combustion engines. Borg Automotive assesses the role that EGR valves play in limiting emissions.


  • Pinging (spark knock or detonation): the EGR system is not working, the exhaust port is clogged up with carbon deposit, or the EGR valve has been disabled
  • Rough idle or misfiring: the EGR valve is not closing and is leaking exhaust into the intake manifold
  • Hard starting: the EGR valve is not closing and is creating a vacuum leak into the intake manifold
  • EGR failure can’t be predicted in a specific timeframe or distance (km). In fact, it can vary based on the type of driving. City driving, for instance, can increase the chance of EGR failure
  • EGR failure can be identified by using specific diagnostic tools or testing the EGR valve

“The initial answer to the emission challenge has primarily been turbo chargers and EGR valves. However, in the coming years we will see 48V systems, kinetic solutions and experimental approaches before the car eventually gets fully electrified. But until then, EGR valves will be an essential part of the solution to drive emissions down”, says Kristian Vesth, Export Manager.

Elstock, a brand of Borg Automotive, claims it was one of the first companies to remanufacture EGR valves, which are now in their fourth generation, starting off with the purely mechanical versions and developing into the electronically controlled units used today. The combination of the increased stress on the EGR and the complexity in technology, demand both an in-depth understanding of the product and a constant improvement of the remanufacturing process.

What is important to know is that the surrounding parts inside the engine affect the condition of the EGR valve. Therefore, if the engine is not properly investigated and tested during the EGR replacement, a remanufactured EGR will only have a short life, as its failure is not determined by the quality of the EGR, but by the underlying cause of the original failure. As an example, the diesel injectors could get to the end of their life expectancy, causing extensive pollution and bringing the EGR to a premature failure. This underlines the need for skilled mechanics during the car repair process to avoid these problems.


Elstock argues that the remanufacturing process gives a unique opportunity to inspect and map common and often-experienced faults and imperfections in the original design and construction of a product. By investigating and solving issues experienced in original products, the company can provide longer life remanufactured EGR valves, compared to original counterparts.

Kristian Vesth elaborates, “Based upon our thorough inspection of defective EGR valves, we have seen that the teeth on original EGR valves are often worn out too soon and are commonly the reason for EGR valve breakdown. Due to the inspection, our engineers were quickly able to conclude the teeth were made of too weak a material, which meant the teeth were not strong enough to tolerate the constant abrasion. To solve this problem, Elstock has developed and implemented its own teeth, which can stand the abrasion much longer”.

The process

The remanufacturing process of EGR valves is carefully executed, and thus needs special
attention throughout. This is due to the advanced and challenging cleaning process which each EGR valve demands.

First, the EGR valves are disassembled and each individual unit is evaluated to see if the individual spare parts are strong enough to be recycled and meet the standards of original over-the-counter parts and the specifications Elstock expects. Second, all parts and different units are gently cleaned to remove all dirt and residue. This, along with many other processes, is vital in ensuring each EGR valve gets a new and long lifespan on the UK’s roads.

To request further details about the range of remanufactured EGR valves available from Borg Automotive, click here.

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