UN R41 Supplement 12 (04 series) · UNECE Regulation No. 41 (ECE R41) — Uniform provisions concerning the approval of motorcycles with regard to noise.
UN R41 — Supplement 12 to the 04 series of amendments
Supplement 11 → 12
- What changed
- The rule in paragraph 6.3.1. against a device or procedure used to pass the noise tests now also names software.
- New paragraph 8.4. covers conformity of production tests in which awot,ref cannot be reached with the same gear as in type approval tests. This applies only if the cause is substantially different barometric pressure, humidity, temperature or rider mass.
- In this case, the gear selection requirement of Annex 3 prevails, and the conformity of production tests can use an acceleration different from awot,ref.
- Why
- IMMA prepared the proposal to strengthen the provisions against test defeating and to make conformity of production testing easier.
- Paragraph 6.3.1. is to make sure that what is tested during approval shows how the vehicle will behave in real-world traffic.
- Changed meteorological conditions and rider mass can make ±10 percent of awot,ref impossible to respect in conformity of production tests with the type approval gear.
Q1What changed2 changes
Devices, procedures or software used to pass the tests (para. 6.3.1.)
The motorcycle manufacturer must not use a device, procedure or software that meets two conditions. First, it would modify noise related functional parameters of the vehicle for the purpose of passing the tests of this Regulation. Second, it would give higher noise emissions in typical on-road operation in the RD-ASEP control range of Annex 7, paragraph 2.5., than during testing. Before this supplement, the manufacturer could not intentionally alter, adjust or introduce any device or procedure solely to fulfil the noise emission requirements. That rule applied to a device or procedure that will not be operational during typical on-road operation.
Conformity of production when awot,ref cannot be reached (para. 8.4.)
New paragraph 8.4. refers to the reference acceleration awot,ref defined in paragraph 1.3.3.3.1.2. of Annex 3. It applies when awot,ref cannot be reached with the same gear in conformity of production as in type approval tests. This applies only if the cause is substantially different barometric pressure, humidity, temperature or rider mass. In this case, the gear selection requirement of paragraph 1.3.3.3.1.3.1. of Annex 3 must prevail. The conformity of production tests can then use an acceleration different from awot,ref.
Q2Why it changed
- Proposed by
- Experts from the International Motorcycle Manufacturer Association (IMMA)
- Working party
- GRBP, 81st session (February 2025)
Reasons
IMMA prepared the proposal to strengthen the provisions against test defeating and to make conformity of production testing easier.
Source
“in order to strengthen provisions against test defeating and to facilitate the Conformity of Production testing.”
Paragraph 6.3.1. is to make sure that what is tested during approval shows how the vehicle will behave in real-world traffic. The proposed text adds software as one of the potential applications of concern.
Sources (2)
“Paragraph 6.3.1. is about ensuring that whatever is tested during the approval is representing how the vehicle will behave in real-world traffic.”
“The proposed text adding ‘software’ as one of the potential applications of concern.”
According to the proposer, the prescribed test conditions of Annex 3 and Annex 7 are part of the wide range of typical on-road operations. For this reason, the detection of these test conditions should not be seen as prohibited as such. This is true as long as the related adjustments that lower the sound emissions are not strictly limited to these test conditions.
Sources (2)
“This is important because the prescribed test conditions (in Annex 3 and Annex 7) are part of the wide range of “typical on-road operations”.”
“a detection of these test conditions may not be considered as being prohibited as such, as long as related adjustments of vehicle parameters with effect of lowering the sound emissions are not strictly limited to these “test conditions”.”
For conformity of production, paragraph 8.2. asks for the same gear and pre-acceleration distance as in the original type approval test. The method of Annex 3 also specifies the target acceleration awot,ref.
Sources (2)
“Paragraph 8.2 asks for the CoP sound levels (Lurban and Lwot) to be measured and processed according to the method described in Annex 3, with the same gear(s) and pre-acceleration distance(s) as used in the original type approval test.”
“The method in Annex 3 however also specifies the target acceleration (awot, ref).”
Meteorological variables such as humidity and barometric pressure can change vehicle performance, and UN Regulation No. 41 does not consider them. In some cases, changed meteorological conditions and rider mass can make it impossible to respect ±10 percent of awot,ref. This can happen if the same gear is used in type approval and conformity of production tests.
Sources (2)
“Meteorological variables such as humidity and barometric pressure can result in variations of vehicle performance and are not considered by UN Regulation No. 41.”
“it may not be achievable to respect ±10 percent of the reference acceleration awot,ref , if the same gear is used in TA and CoP tests.”
Document trail
- 2024-12ProposalECE/TRANS/WP.29/GRBP/2025/6Proposal by IMMA
- —RevisedGRBP-81-30Proposal by IMMA, replacing GRBP/2025/6
- —Working party adoptsECE/TRANS/WP.29/GRBP/79Session report, para. 5
- 2025-04Sent to WP.29ECE/TRANS/WP.29/2025/69Text that GRBP sent to WP.29 and AC.1
- 2025-06WP.29 adoptsECE/TRANS/WP.29/1186Adopted at the 196th session (session report, para. 111)
- 2026-01-11In forceC.N.24.2026.TREATIES-XI.B.16.41UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Review your devices, procedures and software that modify noise related functional parameters against the amended paragraph 6.3.1.
- Update your conformity of production test plans for the case described in paragraph 8.4.
Component supplier
- Check the noise related software that you supply against the new text of paragraph 6.3.1.
Technical service / Approval authority
- Update your checks for paragraph 6.3.1. so that they also cover software.
- Be ready for conformity of production tests that use an acceleration different from awot,ref under paragraph 8.4.
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ⓘ This report gives advice only. It is not legal or type-approval advice.
More UN R41 change reports
- 06 series — Supplement 1
- 06 series — Base text
- 05 series — Supplement 5
- 05 series — Supplement 4
- 05 series — Supplement 3
- 05 series — Supplement 2
- 05 series — Supplement 1
- 05 series — Base text
- 04 series — Supplement 13
- 04 series — Supplement 11
- 04 series — Supplement 10
- 04 series — Supplement 9
- 04 series — Supplement 8
- 04 series — Supplement 7