Why there will be no hardware refurbishment for diesel cars as soon as possible

With a catalytic converter, independent aftermarket engineers want to clean up the diesel, but manufacturers are reluctant. That’s the way the story is told. However, the technical details of a hardware update for diesel passenger cars offer a different interpretation.

An exhaust is equipped with a diagnostic probe for exhaust gas measurement in diesel vehicles

The diagnosis may be, that diesel cars emit too much NOx, but the treatment that results is still unclear.

Photo: panthermedia.net/Corepics

Hardware upgrades may seem off-vehicle as an efficient solution for exhaust aftertreatment, but the complexity of vehicles takes the business ad absurdum. This is the result of a study in which five habilitated engineers on behalf of the Federal Ministry of Transport “analyzed the basic feasibility of a hardware-related conversion, in particular the exhaust aftertreatment” by OEM. The scientists recommend software updates for both Euro 5 and Euro 6 diesel engines instead of technical retrofits. At least when it comes to cars and vans.

We have discussed this with the engine expert and co-author of the study, Thomas Koch, which correlates and structural conditions mean that researchers are less likely to trust hardware upgrades than software updates. Since 2013, the mechanical engineer has headed the Institute for Piston Machines at the Karlsruhe Institute of Technology (KIT), and is also a member of the VDI Advisory Board for Propulsion and Energy Management.

In our conversation, three things became clear:

  • In the debate, we need to differentiate between cars and vans on one side and trucks and buses on the other.
  • In addition, we can not use the technical systems that are designed to retrofit the powertrain as stand-alone Look at the solution. But as a technical element to be added to an already highly complex model. Which leads us to the first reason why there are not yet any marketable hardware solutions for retrofitting diesel vehicles.
  • We have to ask ourselves who fits any solution into the vehicle: the OEM or an independent aftermarket. The answer also provides a significant indication of the costs incurred and the liability problem.
  • Each retrofit solution is an integrative element

    Exhaust aftertreatment, no matter what Fasson, is not a catalyst. which you simply flanged to the exhaust system. Rather, it is “a highly integrative element of the entire vehicle that needs to communicate with the vehicle,” says Koch. “You can not just solder a cable somewhere. If a vehicle manufacturer makes a conversion, cable sets must be replaced and secured beforehand, otherwise errors will occur in the field. “All these interactions are basically to get a grip on, but that is time consuming and it is expensive.

    About because the retrofit has to be connected to the on-board diagnostics (OBD) systems. Or because the exhaust system, which is to be reinforced by the catalysts, is a crashrelevantes component. This means that not only major modifications have to be carried out, but also new safety tests such as a completely new crash test. Here are two more serious problems:


    And then Koch points to a problem that was almost inherited in the cradle of diesel and now in the question of hardware upgrades at Euro -5 diesels stands in the way of some solutions. Namely those who rely on the urea solution AdBlue in the exhaust aftertreatment. “On the one hand you want an efficient engine with a low exhaust gas temperature, on the other hand you need a high exhaust gas temperature to dose the AdBlue,” says Koch.

    For suppliers of AdBlue-based retrofit solutions, this means that their solutions need heaters, to make them work. Because the exhaust temperature in city traffic does not come to the required minimum temperature of 180 ° C, the AdBlue needed to work. Or. to prevent the addition of biuret, amylin or melamine contaminants that build up in the combustion chamber. “But if you add an additional heating catalyst, older vehicles will have an increased on-board network load and the batteries will go to their knees,” Koch explains.