Overview
ISO 3929:2003 specifies direct measurement methods for exhaust gas emissions from road vehicles during inspection or maintenance. It applies to vehicles with a maximum authorized total mass (ISO-M08, per ISO 1176) not exceeding 3.5 t, equipped with controlled-ignition engines, and excludes vehicles supplied with a fuel/oil mixture. The standard supports periodic inspections in official garages, roadside checks (for example by police), and maintenance or diagnostic operations.
Practical value: the standard provides repeatable, field-applicable procedures that improve diagnostic accuracy, support regulatory enforcement and help maintain vehicle emission control performance.
Key Topics
- Scope and applicability: Vehicles ≤ 3.5 t with controlled ignition engines; excludes fuel/oil-mix supplied engines.
- Instrumentation requirements:
- Analysers conforming to ISO 3930/OIML R 99.
- Engine oil temperature meter: accuracy at least ±2 K between 343 K and 373 K.
- Pulse revolution counter: accuracy at least ±20 min⁻¹ between 600 and 1 000 min⁻¹, ±50 min⁻¹ outside that range.
- Ambient temperature meter: accuracy at least ±2 K between 278 K and 313 K.
- Pre-test checks and maintenance: Power supply, zero and span calibration for analysers, and routine periodic maintenance per manufacturer instructions and national regulations.
- Vehicle verification and conditioning: Exhaust system leak checks (e.g., ISO 16247 or sealing the outlet while idling), warm-up to normal thermal conditions (at least 15 min of urban driving or per manufacturer guidance) and minimum lubricant temperature of 353 K in the sump or reservoir.
- Sampling details: Insert the sampling probe at least 300 mm into the exhaust outlet pipe; where multiple outlets exist, either connect to a single outlet or use the arithmetic average of individual outlet measurements.
- Measured-value corrections: For engines with secondary air injection, CO and HC measurements may require correction according to national requirements.
Applications
ISO 3929:2003 is intended for:
- Periodic vehicle inspections in official garages.
- Official roadside emission checks and enforcement.
- Maintenance, repair and diagnostic procedures in workshops.
Benefits include consistent test execution, reliable measurement data for emissions diagnostics, and support for regulatory conformity and environmental protection efforts.
Related Standards
- ISO 3930/OIML R 99 - Instruments for measuring vehicle exhaust emissions (analyser requirements).
- ISO 16247 - Detection of exhaust system leaks (helium test method and device specification).
- ISO 1176 - Road vehicles - Masses - Vocabulary and codes (definition of ISO-M08).
For implementation, follow the standard's instrument checks, vehicle warm-up and measurement sequences to ensure reproducible, comparable emission readings during inspection and maintenance operations.