The difference between ECE R48 and R148 explained

ECE R48 and ECE R148 are regularly mixed up in practice. Yet the two regulations regulate fundamentally different matters. R48 deals with the installation of lighting on the vehicle. R148, on the other hand, deals with the technical requirements for the light-signalling devices themselves. In this article, we briefly outline the difference and show how the two regulations work together in practice.

In this article you will read about the difference between the two schemes, how they work together in practice and what you should pay attention to when purchasing and mounting. Want to understand the wider context first? Then also take a look at our explanation of ECE R48.

What is the difference between ECE R48 and R148?

In short: ECE R48 determines where lighting should be on a vehicle and how mechanics should install it. ECE R148, on the other hand, specifies which technical details the light-signalling devices themselves must have before they receive approval.

R48 looks at the overall picture on the vehicle: which light functions are mandatory, where they must be positioned, at what angle they must be visible, and how they interact with one another. R148 then examines the individual product: does the indicator provide sufficient light, is the colour of the brake light correct, and does the unit continue to function in the face of vibrations and moisture?

Aspect	ECE R48	ECE R148
Topic	Installation on the vehicle	Technical requirements on the light
Level	Vehicle level	Product level
Examples	Placement, height, symmetry, visibility angles	Light colour, light output, durability, photometry
Categories	M, N, O (and more)	Light signalling devices on vehicles in these categories
Required for	Vehicle manufacturers, body builders	Lamp manufacturers and suppliers

What does ECE R48 regulate?

ECE R48 is the UNECE regulation for the installation of lighting and light-signalling devices on vehicles. The regulation determines for each vehicle category which lighting is mandatory, optional or prohibited. In addition, R48 sets requirements on how mechanics apply such lighting. UNECE published Revision 13 on 3 December 2024, which currently shapes the version in force.

R48 regulates, among other things:

• which light functions are mandatory or permitted per vehicle category
• placement in width, height and length on the vehicle
• geometric visibility angles within which lights must remain visible
• symmetry between left- and right-hand side of the vehicle
• electrical switching between different light functions

R48 is therefore particularly relevant for vehicle manufacturers, bodybuilders and vehicle builders who carry out the surface mounting and final inspection of vehicles. You can read more about this in our full explanation of ECE R48.

What does ECE R148 regulate?

ECE R148 governs the approval of light-signalling devices (lamps for light-signalling) on motor vehicles and their trailers. The UNECE introduced R148 in 2019 to consolidate the technical requirements from several older light-signalling regulations into a single, simplified regulation, including R4, R6, R7, R23, R38, R50, R77, R87 and R91. This resulted in a streamlined set of regulations without altering the substance of the underlying technical requirements.

R148 regulates, among other things:

• indicator (formerly R6)
• Brake lights and position lights (formerly R7)
• Licence plate lighting (formerly R4)
• Reversing lights (formerly R23)
• Rear fog lights (formerly R38)
• Parking lights and side marker lights (formerly R77 and R91)
• Position lights (DRL, formerly R87)

The technical requirements are mainly about light colour, light output (photometry), light distribution, durability under varying temperature and humidity conditions, and the correct operation of the light during normal use. A light that does not comply with R148 cannot therefore receive UNECE approval for applications in which such certification is required for vehicle type approval or compliant mounting.

How do ECE R48 and R148 work together in practice?

The distinction between R48 and R148 sounds abstract, but in practice it quickly becomes concrete. A light that fully complies with the technical requirements of R148 can still fail inspection if the mounting on the vehicle does not comply with R48. The same applies the other way round: a perfectly placed light will not help if the light unit itself fogs the correct approval.

For fitters and vehicle builders, this means that both regulations must always be considered together. When purchasing lighting, they first check for compliance with R148 (technically certified product). They then verify compliance with R48 (correctly fitted to the vehicle) during surface mounting and the final inspection.

Important: an R148 approval on the light is not a licence for mounting. Only when the installation also complies with R48 does the complete vehicle lighting comply with the regulations.

Example: side marker lights on a trailer

To illustrate — a side marker light on a trailer must comply with both regulations. Firstly, R148 sets out the technical requirements for the light itself: the light colour must be amber , the light output must fall within specified limits, and the light must continue to function under varying conditions. R48 then specifies where that light must be positioned on the trailer : at what height, at what spacing, within what angles of visibility, and in what symmetry relative to the other side.

Take, for example, a light with the correct R148 approval that a mechanic fits at the wrong height. In that case, the installation does not comply with R48. The trailer will then fail its roadworthiness truck, even though the light is technically fully compliant.

The key R48 mounting requirements for truck and semi-trailers in a short overview

Requirement	Value
Side marker lights are compulsory	Vehicles longer than 6 metres
Number of side marker lights	At least 2 per side
Maximum spacing between side marker lights	3 metres
Mounting height of side marker lights	Typically between 250 and 1500 mm

What do you look out for as a buyer or mechanic?

Anyone who performs surface mounting on commercial vehicles or purchases lighting for the semi-trailer and lorry industry would be well advised to embed both regulations systematically into their work processes. In practice, we see that most inspection failures are not caused by non-certified lights, but rather by fitting errors — positioning just outside the permitted margin, uneven symmetry lines, or visibility angles that fall just short of the required standard.

In procurement (R148 control):

• Check whether the light has a valid E-mark referring to R148
• request the type approval certificate from the manufacturer or supplier
• In addition, check whether the light meets additional requirements such as ECE R10 (EMC) if it operates electronically

On mounting (R48 control):

• first check the positioning in width, height and length according to the prescribed values
• then truck the symmetry between left and right
• Also consider the visibility angles – particularly for contour marking and side marking
• Finally, truck the correct electrical switching between light functions

When it comes to LED indicators, bear in mind an additional R48 requirement: the regulations stipulate that a faulty indicator must be signalled to the driver. Because LED lights draw much less current than incandescent lights, the vehicle’s electronics do not always correctly detect a fault or even a functioning LED light. When replacing or performing surface mounting, a load detection solution is therefore often required. You can read how this works in our article on CAN-bus fault messages for LED lighting.

For specific practical guidelines, you’ll also find a comprehensive guide to fitting instructions for trailer lighting and an overview of the regulations for trucks and semi-trailers in our knowledge base.

ECE R48, R148 and R149: a broader overview

For the sake of completeness: in addition to R48 and R148, there is also ECE R149. This regulation sets out the technical requirements for road illumination devices – lighting that makes the road visible to the driver, such as headlights and front fog lights. R148, on the other hand, focuses on light-signalling devices that ensure other road users can see the vehicle, including indicators, brake lights, position and parking lights, side marker lights, reversing lights, rear fog lights and position lights (DRL). In short: R149 concerns lighting for seeing, whilst R148 concerns lighting for being seen.

In combination, these three schemes therefore shape the framework for modern vehicle lighting in Europe:

• ECE R48 - installation on the vehicle
• ECE R148 - technical requirements for light signalling devices
• ECE R149 - technical requirements for road lighting devices

Anyone selecting lighting for a commercial vehicle therefore keeps all three in mind. For EMC requirements (electronic susceptibility to interference), ECE R10 must also be taken into account.

The introduction of R148 in 2019 brought nine separate regulations together into a single, clear framework. In practice, this meant the end of fragmented administration.

Frequently asked questions

What is the main difference between ECE R48 and R148?

ECE R48 deals with the installation of lighting on the vehicle (placement, height, visibility angles, symmetry). ECE R148, on the other hand, deals with the technical requirements of the light-signalling devices themselves (light colour, light output, durability). In short, R48 sets the rules for the vehicle, R148 for the product.

Does a light have to be R48 and R148 compliant?

Legally, the regulations focus on different issues. As a product, a light unit must comply with R148. In contrast, R48 does not apply to the light as a separate product, but to its installation and operation on the vehicle. In short, an R148 approval covers the product, while R48 compliance determines how the light operates on the vehicle.

Which old regulations does R148 replace?

Since 2019, R148 has consolidated the technical requirements from nine older UN regulations: R4 (number plate lamps), R6 (indicators), R7 (position, brake and end-outline lights), R23 (reversing lights), R38 (rear fog lights), R50, R77 (parking lights), R87 (position lights) and R91 (side marker lights). Existing type approvals under these older regulations remain valid.

Do R48 and R148 also apply to trailers and semi-trailers?

Yes. R48 applies to vehicles in categories M, N and O — which also includes trailers and semi-trailers in category O. R148 also applies to all light-signalling devices on these vehicles, including the lights fitted by mechanics to trailers and semi-trailers.

Want to know more about ECE regulations and vehicle lighting?

TRALERT® supports OEMs, vehicle builders and other professionals with ECE-certified LED lighting for commercial vehicles. Our lighting complies with R148, ensures correct installation in accordance with R48, and is available for all standard categories of lorry and trailer lighting. Please contact us for technical advice or explore our knowledge base further through the comprehensive explanation of ECE R48 or the broader context of ECE standards and legislation.