EU’s WLTP test procedure to turn tougher from September

by Autocar Pro News Desk , 21 Jun 2019

A major change in WLTP Stage II is the measurement of whether the emission limits are still met during vehicle operation. VW uses a mobile exhaust gas measurement lab for on-site measurements.

Euro 6d TEMP EVAP ISC – this is the complicated name of the emission standard that will be mandatory for all newly registered vehicles with the second stage of the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) type test from September 1 2019 in the EU.

The WLTP procedure introduced last year will be further tightened by new technical requirements and the technical procedures involved in type testing will be increased yet further.


In this process, the abbreviation ’EVAP’ (evaporative emissions) stands for the verification of evaporative emissions. An activated charcoal filter in the tank system already prevents petrol vapours from being released into the environment of Volkswagen models. In the past, this was tested in an airtight chamber for 24 hours. In the future, however, the period will be 48 hours – at constant limit values. The vehicles will be retrofitted with technology to meet these additional requirements.

Another major change with the second WLTP stage is the measurement of whether the emission limits are still met during vehicle operation. In future, vehicles up to five years old will be subjected to a random WLTP test. This field monitoring (ISC = InServiceConformity) is carried out on selected vehicles with a mileage of up to 100,000 kilometres. Volkswagen also uses a mobile exhaust gas measurement laboratory for on-site measurements of customer vehicles.

The first WLTP stage came into force for all new vehicles on 1 September 2018. The fact that the next stage follows just one year later – and there will be others – is due to the procedure's high complexity. The regulations, which will come into force in September 2019, also contain details about the previous procedure and thus provide legal certainty.