How Germans convert Euro 5 diesel cars to Euro 6 to keep them on the road

Diesel vehicles in Romania have seen exhaust aftertreatment systems removed become commonplace, especially on high-mileage examples. This trend has shaped how owners approach aging diesels and the local perception of emissions and maintenance.

In contrast, Germany has chosen a completely different path: official conversions that bring older vehicles up to Euro 6 standards, often incorporating AdBlue and modern sensors, carried out by specialized companies.

Reality in Romania: removal of exhaust aftertreatment systems

In our country, an “unwritten law” has emerged that almost every BMW with over 300,000 kilometers should not have a DPF installed. This practice has spread to most brands and has become a real tradition among diesel owners.

Owners choose to remove the DPF without considering:

• The significant increase in pollution
• Unpleasant odors from the exhaust
• Gas infiltration into the cabin
• The illumination of warning lights on the dashboard
• The inability to pass the legally required inspection (ITP)

Although from the outside the car retains the appearance of a premium vehicle, technically and environmentally it becomes a veritable “garbage” that many would not invest any money in.

The German approach: official conversions to higher standards

In Germany, the automotive industry has developed a completely different approach. Instead of removing exhaust aftertreatment systems, specialized companies offer conversion services that transform older vehicles to comply with stricter emission standards.

Differences between emission standards

Euro 5 standards (mandatory since January 2011):

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• CO: 0.50 g/km
• HC + NOx: 0.23 g/km
• NOx: 0.18 g/km
• PM: 0.005 g/km
• PN [#/km]: 6.0x10^11/km

Euro 6 standards (current standard):

• CO: 0.50 g/km
• HC + NOx: 0.17 g/km
• NOx: 0.08 g/km (55% significant reduction)
• PM: 0.005 g/km
• PN [#/km]: 6.0x10^11/km

For comparison, a vehicle with DPF off (Euro 0/1):

• CO: 2.72 g/km
• HC + NOx: 0.97 g/km
• PM: 0.14 g/km

The difference is dramatic - a vehicle without exhaust aftertreatment system pollutes with respect to fine particles (PM) 28 times more.

The conversion process in Germany

Available upgrades

• Vehicles Euro 2 or Euro 3 to Euro 5
• Vehicles Euro 5 to Euro 6

Components of the conversion

Software modifications:

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• Reprogramming of the engine control unit (ECU)
• Optimization of injection parameters
• Adjustment of regeneration strategies

Hardware modifications:

• Installation of a new, high-performance DPF
• Installation of the AdBlue system (for Euro 6)
• Upgrade of NOx sensors
• Modernization of the catalytic converter

TÜV certification

All modifications are performed in accordance with TÜV (Technischer Überwachungsverein) standards, which means:

• Strict compliance with technical regulations
• Rigorous emissions testing
• Official certification for road use
• Warranty for system operation

The AdBlue system and its importance

For conversions to Euro 6, vehicles receive the AdBlue system, which:

• Reduces NOx emissions by up to 90%
• Uses a urea solution to neutralize nitrogen oxides
• Is mandatory to meet Euro 6 standards
• Requires periodic refilling (every 15,000–25,000 km)

Reasons for conversion in Germany

Economic factors

• Preserving a valuable investment
• Avoiding the cost of a new vehicle
• Maintaining diesel engine efficiency

Technical factors

• Preserving engine performance
• Proven mechanical reliability
• Adapting to urban restrictions

Environmental factors

• Compliance with low-emission zones
• Contributing to improved air quality
• Alignment with environmental policies

Difference in mentality

While Romania seeks solutions to bypass exhaust aftertreatment systems, Germany invests in technologies to enhance them. This difference in approach reflects:

• Different levels of environmental awareness
• Stricter technical inspections
• Greater importance given to environmental regulations
• A long-term perspective on automotive investments

Germans demonstrate that it is possible to preserve the performance and efficiency of a diesel engine while meeting environmental standards through advanced technology, not by removing protection systems.