PEMS testing is the measurement of exhaust emissions using portable emissions measurement systems (PEMS) installed on a vehicle or machine. These systems measure gases and/or particles during operation on the road, in the field, or in the laboratory. By combining emissions measurements with exhaust-flow and operating data, PEMS testing shows how emissions change with driving conditions, engine load, and the surrounding environment.
HORIBA helps engineers and OEMs evaluate emissions beyond standard laboratory test cycles, investigate engine and aftertreatment performance, and support regulatory testing. Our configurable solutions support real driving emissions (RDE), real-world emissions (RWE) evaluation, and in-use testing for light-duty vehicles, heavy-duty vehicles, and non-road mobile machinery (NRMM), helping development teams identify emissions challenges and assess improvements under representative operating conditions.
A PEMS installation brings emissions measurement equipment on board the vehicle or machine. Depending on the configuration, it can measure gaseous emissions, particle number, or particle mass, alongside exhaust-flow and supporting operating data.
Combining these signals allows engineers to relate emissions to changes in speed, load, route, and environmental conditions. The components measured and the result calculations depend on the test objective and applicable procedure.
| Measurement | Purpose |
|---|---|
| Gaseous emissions | Evaluate components such as CO, CO2, NOx, and hydrocarbons; selected systems extend measurement to NH3, N2O, HCHO, and CH4. |
| Particle emissions | Assess particle number or particle mass with the appropriate measurement module. |
| Exhaust flow | Combine flow and concentration data to calculate gaseous mass emissions. |
| Vehicle, engine, & location data | Connect emissions with operating conditions and the test route. |
| Environmental conditions | Record temperature, pressure, and humidity to support evaluation of test conditions. |
PEMS testing complements laboratory exhaust emissions testing by extending measurement into actual vehicle and machinery operation.
Temperature, altitude, vibration, and rapidly changing engine operation make real-world testing particularly demanding. Measurement systems must perform reliably within their specified operating conditions while capturing changes in emissions.
Key considerations include:
Passenger cars, trucks, and off-highway machinery present different installation constraints. Equipment location, mounting, power supply, and sampling connections must suit the application without compromising safety or affecting operation.
Key considerations include:
Useful emissions results require correctly aligned measurement and operating data. Signal delays, data gaps, and invalid test conditions must be identified to connect emissions with vehicle or engine activity and evaluate results against regulatory quality criteria.
Key considerations include:
Compact Emissions Measurement System
On-board Emissions Measurement System
On-board NH3/N2O Measurement System for real-world driving
On-board Emissions Measurement System
On-board SPN10 measurement for real-world
On-board Emissions Measurement System
Protection Case for Testing Heavy-Duty and Non-Road Mobile Machinery
Software for Laboratory Management
Test Automation Software for Emission Testing
Real-world measurement can reveal emissions behavior that needs further investigation under repeatable conditions. Combining emissions results with drive-recording data helps engineers identify relevant operating events for laboratory development.
HORIBA’s Intelligent Lab supports road-to-rig development approaches, including torque matching and empirical digital twins. These approaches help teams investigate real-world behavior, evaluate calibration changes, and compare results in a controlled environment.
The following resources explain how PEMS is used and provide guidance for specific testing applications. Requirements differ by region and vehicle or engine category.
Understanding PEMS: European Commission overview explains portable emissions measurement and its role in real-world in-use testing.
Light-duty vehicle RDE testing: European Commission on-road testing guidance provides practical recommendations for preparing, conducting, and evaluating PEMS tests. Published in 2018, it should be used alongside current regulations.
U.S. engine field testing: 40 CFR Part 1065, Subpart J covers PEMS equipment, calibration, verification, and test procedures. Applicability is determined by the standards for the engine category.
EU light- and heavy-duty vehicle emissions: Euro 7 Regulation (EU) 2024/1257 establishes the emissions framework; detailed testing requirements are set out in the applicable implementing legislation.
VCA approval: MEXAcube has received UK Vehicle Certification Agency approval as an alternative analyzer under UN Regulation No. 168. Read the approval announcement.
PEMS testing measures emissions during actual vehicle or machinery operation, where speed, load, and environmental conditions vary. Laboratory testing provides controlled conditions for repeatable tests and comparisons. The methods complement each other: real-world testing evaluates operation on the road or in the field, while laboratory testing supports controlled investigation. Portable systems can also be used in laboratories when the applicable requirements are met.
For RDE testing, PEMS equipment is installed on a vehicle to record emissions during an on-road trip. Emissions measurements are combined with exhaust-flow and supporting data, such as speed, location, and environmental conditions. The results are evaluated using the applicable procedure, including checks on test conditions and data quality. RDE is a defined testing procedure; PEMS is the measurement equipment used to carry it out.
Yes. PEMS can measure emissions from heavy-duty vehicles and non-road mobile machinery during operation. The equipment configuration, measured components, installation, and evaluation methods must suit the application. On-road routes and off-highway working cycles present different conditions, so the relevant testing requirements should guide system selection.
Planning an RDE test, evaluating in-use emissions, or investigating a development challenge? Share your vehicle or machinery type, target emissions components, testing conditions, and data requirements using the form below. HORIBA can help identify a suitable measurement configuration for your application.
Do you have any questions or requests? Use this form to contact our specialists.
