Order;Information — ECLI:EU:C:2026:170
Date: 2026-03-03
Language of the case: German
Court formation: Ninth Chamber
Procedure: Reference for a preliminary ruling
Origin: Austria

Anonymised version 
Translation C-526/25 – 1 
Case C-526/25 
Request for a preliminary ruling 
Date lodged: 
5 August 2025 
Referring court: 
Bezirksgericht Steyr (Austria) 
Date of the decision to refer: 
22 July 2025 
Applicant: 
XV 
Defendant: 
Volkswagen AG 
  
[…] 
REPUBLIC OF AUSTRIA      […] 
BEZIRKSGERICHT STEYR (District Court, Steyr, Austria) 
ORDER 
CASE: 
Applicant  
XV  
[…] Enns 
[…] 
Defendant  
Volkswagen AG […] 
Wolfsburg  
[…] 
EN 
REQUEST FOR A PRELIMINARY RULING OF 22. 7. 2025 – CASE C-526/25 
 
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GERMANY 
concerning: EUR 3 640.00 
I. The proceedings shall continue. 
II. The following questions are referred to the Court of Justice of the European 
Union for a preliminary ruling pursuant to Article 267 TFEU: 
1. Must Article 2(6) of and Annex III, section 3.13.4 to Implementing 
Regulation (EC) No 692/2008 (in conjunction with Article 3(10) of Regulation 
(EC) No 715/2007) be interpreted as meaning that a pollution control device 
(control programme for the regeneration of the storage catalyst in the preparation 
cycle), which is deemed to be a continuously regenerating system because 
regeneration (cleaning process) occurs at least once per type I test, and the device 
has already regenerated at least once during the vehicle preparation cycle (Precon 
or preconditioning), is a defeat device within the meaning of Article 3(10) of 
Regulation (EC) No 715/2007? 
2. (a) Must Article 5(2)(c) of Regulation (EC) No 715/2007 (in conjunction with 
Article 3(10) of Regulation (EC) No 715/2007 and Article 2(6) of and Annex III, 
section 3.13.4 to Implementing Regulation (EC) No 692/2008) be interpreted as 
meaning that (if so) such a defeat device is permissible because the conditions are, 
in essence, included in the relevant emissions test procedure? 
(b) Must Article 5(1) of Regulation (EC) No 715/2007 (in conjunction with 
Article 3(10) of Regulation (EC) No 715/2007 and Article 2(6) of and Annex III, 
section 3.13.4 to Implementing Regulation (EC) No 692/2008) be interpreted as 
meaning that (if so) such a defeat device is permissible if the emission-related 
operation it exhibits in the test procedure (approval test) is present in the majority 
of cases, even in normal use (in real-life operation)? 
3. Must paragraph 2.20. of and Annex 13, paragraph 3 to the UNECE 
Regulation (in conjunction with Annex III, section 3.13.1 to and Article 2(6) of 
Implementing Regulation (EC) No 692/2008) be interpreted as meaning that the 
arrangement laid down in the second sentence of Annex 13, paragraph 3 to the 
UNECE Regulation, in accordance with which the switch (to prevent or permit the 
regeneration process) may be activated during preconditioning cycles only in 
order to prevent regeneration, applies only to the special test procedure provided 
for in Annex 13 to the UNECE Regulation and thus to the emissions testing of a 
vehicle with a periodically regenerating system and not also in respect of a vehicle 
with a continuously regenerating system? 
III. […] [stay of proceedings] 
GROUNDS: 
VOLKSWAGEN 
 
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1 The proceedings at issue were stayed pending the decision on the request for a 
preliminary ruling made by the Oberster Gerichtshof (Supreme Court, Austria) 
under 8 Ob 14/24b (C-609/24), 3 Ob 137/24d (C-624/24), and 3 Ob 117/24p 
(C-561/24), and by the Bezirksgericht Graz-Ost (District Court, Graz-Ost, 
Austria) under 206 C-547/21v (C-559/24). Those cases were combined for a joint 
decision. On account of an agreement between the parties, the relevant legal issues 
have not been clarified. 
2 […] 
3 On 11 April 2019, the applicant purchased a VW Passat Variant Comfortline TDI 
for a purchase price of EUR 18 200.00. The vehicle is equipped with an EA 288 
engine (EU-6 NSK) – including a NOx storage catalytic converter. The engine of 
the vehicle is equipped with a ‘Precon’ (preconditioning), which consists of a 
control programme for driving curve detection with test cycle-dependent 
regeneration of the NOx storage catalytic converter. That catalytic converter is 
able to store chemically a certain proportion of the nitrogen during normal 
driving. It must be regenerated regularly by combustion to maintain its 
functionality. Regeneration takes place after a certain distance travelled or when 
the catalytic converter is fully saturated during ongoing operation. The vehicle 
recognises preconditioning (Precon). The preconditioning (Precon) is recognised 
by the engine control unit and the NOx storage catalytic converter is regenerated. 
The test cycle therefore begins with a freshly regenerated NOx storage catalytic 
converter. That leads to two regenerations of the NOx storage catalytic converter 
during the approximately 11-kilometre long driving curve in the 1.180 seconds of 
the test cycle and not – as would be the case without regeneration in the 
preconditioning phase – to a possible three regenerations. In purely mathematical 
terms, regeneration can occur more than twice in real-life operation, which is 
associated with a short-term increase in pollutants. 
4 Regulation (EC) No 715/2007 on type approval of motor vehicles with respect to 
emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and 
on access to vehicle repair and maintenance information: 
‘Article 3(10): 
For the purposes of this Regulation and its implementing measures the following 
definitions shall apply: 
“defeat device” means any element of design which senses temperature, vehicle 
speed, engine speed (RPM), transmission, gear, manifold vacuum or any other 
parameter for the purpose of activating, modulating, delaying or deactivating the 
operation of any part of the emission control system, that reduces the effectiveness 
of the emission control system under conditions which may reasonably be 
expected to be encountered in normal vehicle operation and use’. 
Commission Regulation (EC) No 692/2008 implementing and amending 
Regulation (EC) No 715/2007/EC (‘the Implementing Regulation’): 
REQUEST FOR A PRELIMINARY RULING OF 22. 7. 2025 – CASE C-526/25 
 
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‘Article 2(6): 
For the purposes of this Regulation, the following definitions shall apply: 
“periodically regenerating system” means catalytic converters, particulate filters 
or other pollution control devices that require a periodical regeneration process in 
less than 4 000 km of normal vehicle operation. 
Annex III: Verifying average exhaust emissions at ambient conditions 
… 
3. Technical requirements 
3.13. Technical requirements for a vehicle equipped with a periodically 
regenerating system 
3.13.1. The technical requirements shall be those set out in section 3 of Annex 13 
to UN/CE Regulation No 83, with the exceptions described in sections 3.13.2 to 
3.13.4. 
… 
3.13.4. For a periodically regenerating device, during cycles where regeneration 
occurs, emission standards can be exceeded. If a regeneration of a pollution 
control device occurs at least once per type 1 test and the device has already 
regenerated at least once during vehicle preparation cycle, it shall be considered as 
a continuously regenerating system which does not require a special test 
procedure.’ 
Regulation No 83 of the Economic Commission for Europe of the United Nations 
(UN/ECE) – Uniform provisions concerning the approval of vehicles with regard 
to the emission of pollutants according to engine fuel requirements (‘the UNECE 
Regulation’): 
‘Paragraph 2.20.: 
For the purposes of this Regulation 
“Periodically regenerating system” means an anti-pollution device (e.g. catalytic 
converter, particulate trap) that requires a periodical regeneration process in less 
than 4 000 km of normal vehicle operation. During cycles where regeneration 
occurs, emission standards can be exceeded. If a regeneration of an anti-pollution 
device occurs at least once per type I test and that has already regenerated at least 
once during vehicle preparation cycle, it will be considered as a continuously 
regenerating system which does not require a special test procedure. Annex 13 
does not apply to continuously regenerating systems. 
VOLKSWAGEN 
 
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Annex 13: Emissions test procedure for a vehicle equipped with a periodically 
regenerating system 
… 
3. Test procedure 
The vehicle may be equipped with a switch capable of preventing or permitting 
the regeneration process provided that this operation has no effect on original 
engine calibration. This switch shall be permitted only for the purpose of 
preventing regeneration during loading of the regeneration system and during the 
pre-conditioning cycles. However, it shall not be used during the measurement of 
emissions during the regeneration phase; rather the emission test shall be carried 
out with the unchanged Original Equipment Manufacturer (OEM) control unit.’ 
5 The decision on the legal dispute depends to a large extent on the interpretation of 
Article 3(10), Article 5(1) and (2) of Regulation (EC) No 715/2007, Article 2(6) 
and Annex III section 3.13.1 and 3.13.4 of the Implementing Regulation as well as 
paragraph 2.20. and Annex 13 paragraph 3 of the UNECE Regulation In the view 
of the Supreme Court, there is no ‘acte clair’ as regards the questions referred for 
a preliminary ruling, which is why a reference for a preliminary ruling to the 
Court of Justice of the European Union is necessary. 
6 It is not disputed in the proceedings that the applicant’s vehicle is equipped with 
an EA 288 diesel engine, which is governed by the Euro 6 exhaust standard. The 
main question in the proceedings is whether the implemented Precon with driving 
curve detection (control programme for the regeneration of the catalytic converter 
in the preparation cycle) is a prohibited defeat device within the meaning of 
Article 3(10) of Regulation (EC) No 715/2007, in conjunction with Article 5 
thereof. 
7 Question 1 relates to whether a continuously regenerating system (unlike a merely 
periodically regenerating system) can be a defeat device at all. The Supreme Court 
assumes that the Precon in question (control program for regenerating the storage 
catalytic converter in the preparatory cycle, so that the actual type I test cycle 
starts with a regenerated catalytic converter) is a continuously regenerating 
system. According to its findings, both the requirements for a continuously 
regenerating system under Article 2(6) of the Implementing Regulation and those 
under Annex III, section 3.13.4 to the Implementing Regulation are met. 
8 Article 2(6) of the Implementing Regulation (the content of which is identical to 
the first sentence of paragraph [2.20.] of the UNECE Regulation) defines the 
periodically regenerating system. Annex III, section 3.13.4. of the Implementing 
Regulation is linked to that provision; the first sentence corresponds to the second 
sentence of paragraph [2.20.] of the UNECE Regulation. The second sentence (the 
content of which is identical to the third sentence of paragraph [2.20.] of the 
UNECE Regulation) defines the continuously regenerating system as a particular 
REQUEST FOR A PRELIMINARY RULING OF 22. 7. 2025 – CASE C-526/25 
 
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form of periodically regenerating system and stipulates that no special test 
procedure is required for a continuously regenerating system. 
9 A distinction must therefore be made between a periodically regenerating system 
and a continuously regenerating system. The special feature of a continuously 
regenerating system is that regeneration occurs at least once per type I test and the 
device has already regenerated at least once during the vehicle preparation cycle. 
10 As it is laid down that a continuously regenerating system does not require a 
special test procedure, Annex 13, paragraph 3 to the UNECE Regulation (in 
conjunction with Annex III, section 3.13.1. to the Implementing Regulation) is not 
applicable. The test procedure provided for in Annex 13, paragraph 3 to the 
UNECE Regulation therefore applies only to vehicles equipped with a 
periodically regenerating system, and not to vehicles equipped with a 
continuously regenerating system. Those connections are undoubtedly confirmed 
by paragraph 2.20. of the UNECE Regulation (the rules of which are identical in 
content). That provision expressly provides that Annex 13 to the UNECE 
Regulation does not apply to continuously regenerating systems. The test 
procedure provided for in Annex 4A to the UNECE Regulation therefore applies 
to a continuously regenerating system. In that case, the exhaust gas measurements 
take place only in the actual test cycle. By contrast, for periodically regenerating 
systems there are further test cycles (preparation cycle; regeneration cycle). 
11 On account of the legal fiction under the second sentence of Annex III, section 
3.13.4 to the Implementing Regulation, according to which the particular form of 
periodically regenerating system described is to be considered as a continuously 
regenerating system, it must be assumed for the test operation (on the test bench) 
that the regeneration system is continuously in operation (throughout) The control 
of the regeneration process must therefore be disregarded for the exhaust gas 
measurement, with the result that, in the Supreme Court’s view, it must be 
assumed that the engine functions (and operates) consistently (uniformly) in 
respect of measurements. 
12 If the uniform functioning of the engine applies to the test operation due to the 
legal fiction described, this must also apply to real-life operation because a 
meaningful comparison with real-life operation (with adverse legal consequences 
in the case of emissions-related changes) is possible only if the same starting 
conditions exist with regard to the functioning of the emission control system. For 
this reason, it seems obvious to assume that, in the case of a continuously 
regenerating system and in real-life operation, the regeneration system operates 
continuously. 
13 This would mean that, as a result of a continuously regenerating system, the 
operation of no part of the emission control system is activated, modulated, 
delayed or deactivated that reduces the effectiveness of the emission control 
system in real-life operation. If this approach were followed, such a continuously 
VOLKSWAGEN 
 
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regenerating system would not be a defeat device within the meaning of 
Article 3(10) of Regulation (EC) No 715/2007. 
14 Questions 2(a) and (b) concern the existence of any justification, even if the 
existence of a defeat device is to be assumed. 
15 Article 5(2)(c) of Regulation (EC) No 715/2007 provides for an explicit (written) 
ground of justification where, despite the defeat device, the conditions are, in 
essence, included in the test procedure in question. Annex III, section 3.13.4 to the 
Implementing Regulation expressly provides for the use of a Precon (control 
programme for the regeneration of the catalytic converter in the preparation cycle) 
and stipulates that, under certain conditions, which are evident in the present case, 
the regenerating system is to be considered as a continuously regenerating system, 
with the result that a type I test must take place. Accordingly, the test conditions at 
issue here point to the applicability of a particular approval test (type I), thus 
during the preparation cycle regeneration of the pollution control device (catalyst) 
must occur at least once. If this condition is imposed in the standards for the 
relevant test procedure, the exemption provided for in Article 5(2)(c) of 
Regulation (EC) No 715/2007 must also apply. 
16 Under Article 5(1) of Regulation (EC) No 715/2007, the components which affect 
emissions must ensure that the vehicle, even in normal use, complies with 
Regulation (EC) No 715/2007, thus in particular that limit values are observed. In 
that connection, in its judgment in Case C-693/18, CLCV, paragraph 99, the 
European Court of Justice held that Article 3(10) of Regulation (EC) No 715/2007 
must be interpreted as meaning that software which alters the level of vehicle 
emissions according to the driving conditions which it detects and ensures 
compliance with emission limits only where those conditions correspond to those 
applied during the approval procedures, constitutes a defeat device, even if an 
improvement in the performance of the emission control system may also be 
observed, occasionally, under normal conditions of vehicle use. This means, a 
contrario, that a defeat device must be permissible where the emissions 
performance in the test cycle is, for the most part or in the majority of cases, also 
present in real-life operation. 
17 That is the case with the Precon at issue because regeneration takes place twice in 
the actual test cycle, whereas in real operation regeneration can take place more 
than twice in purely mathematical terms. In the majority of cases and thus also in 
real-life operation, regeneration of the catalytic converter occurs in such a way 
that the conditions are the same as in the test cycle. 
18 In the opinion of the Supreme Court, if for the most part the pollution control 
device (catalytic converter) operates in the same way in real-life operation as in 
test operation, it cannot be said that pollution control is discernible only 
occasionally in real-life operation. 
REQUEST FOR A PRELIMINARY RULING OF 22. 7. 2025 – CASE C-526/25 
 
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19 Question 3 concerns the objection that the Precon is not a continuously 
regenerating system since the existing switch to prevent or permit the regeneration 
process during the preparation cycle is activated to trigger the regeneration of the 
catalytic converter and not only to prevent it (see Annex 13, paragraph 3 to the 
UNECE Regulation; also see paragraph 3.2.3.). 
20 Although Annex 13, paragraph 3 to the UNECE Regulation applies to a 
periodically regenerating system (with the special test procedure under Annex 13 
to the UNECE Regulation), it does not apply to a continuously regenerating 
system (type I test under Annex 4A to the UNECE Regulation). For a 
continuously regenerating system, Annex III, section 3.13.4. to the Implementing 
Regulation (the content of which is identical to the third sentence of 
paragraph 2.20. of the UNECE Regulation) expressly provides that regeneration 
of the catalytic converter must occur at least once in the preparation cycle also. 
The fact that such regeneration is deliberately triggered and that the actual test 
cycle thus starts with an empty catalytic converter is therefore prescribed and not 
harmful. 
Regarding II: 
[…] [legal basis for the stay of proceedings]