In-Service Conformity (ISC)
This page was last updated on 26th March 2026Light Duty Vehicles (LDV)
Assimilated (EU) Regulation 2017/1151 (as amended) and UNR83.08 set out the In-Service Conformity (ISC) requirements for checking that vehicles continue to meet the applicable tailpipe and evaporative emissions limits in normal use, for up to 5 years or 100,000 km (whichever comes first).
These requirements apply to M and N1 class I vehicles based on types approved after 1 January 2019 and to all vehicles registered after 1 September 2019 and to N1 classes II and III and N2 vehicles based on types approved after 1 September 2019 and registered after 1 September 2020.
Granting Type Approval Authority (GTAA) ISC
The VCA must check the Type 1 and RDE performance of at least 5% of a manufacturer’s ISC families each year, or at least two ISC families per year (where applicable). GTAA ISC testing applies only where annual sales of the ISC family are over 5,000 vehicles in the UK.
Each year, the VCA will contact manufacturers who hold a valid g11 or E11 emissions approval to request sales and warranty data, to confirm which ISC families will be included in the GTAA programme. Please note that all costs incurred by the VCA to deliver GTAA ISC testing are levied on manufacturers in scope for GTAA ISC testing.
Manufacturer ISC
Manufacturers must carry out in-service conformity (ISC) testing for tailpipe emissions for all ISC families, including at least a Type 1 test. They may also carry out RDE, Type 4 and Type 6 tests where appropriate. Testing for a given ISC family must start at least every 24 months, and ISC requirements apply until 5 years after the last Certificate of Conformity is issued. All ISC results must be reported to the VCA’s Conformity of Production Team.
In-Service Conformity (ISC) Heavy Duty Vehicles (HDV)
Assimilated EU Regulation 595/2009 requires the conformity of in-service vehicles or engines within an engine family shall be demonstrated by on-road testing of heavy-duty vehicles, this testing must be representative of real-world conditions. Testing shall be repeated at least every two years for each engine family.
Following the granting of type approval for an engine family, the manufacturer shall carry out in-service testing on that engine family within 18 months of the first registration of a vehicle fitted with an engine from that family. For multi-stage type approval, “first registration” means the first registration of the completed vehicle.
The manufacturer shall submit a test plan to the VCA at the time of the initial type approval of a new engine family, and shall report the results of in-service testing to the VCA, in line with the approved plan.
In-Service Verification (ISV) Light Duty Vehicles (LDV)
EU Regulation 2023/2867 and 2023/2866 establish the In-Service Verification (ISV) of CO2 emissions and fuel consumption values. This process ensures that the values declared on Certificates of Conformity are representative on in-service vehicles. These regulations also allow Granting Type Approval Authorities (GTAAs) to test for vehicle strategies that might artificially improve performance during type-approval tests.
Following the UK’s exit from the EU, the UK retained the legal powers to undertake ISV but did not retain the specific implementing regulations. As a result, the VCA doesn’t have any legal obligations to perform ISV testing. However, as the UK maintains the power to implement ISV testing, we may choose to introduce this in the future following consultation with industry.
In-Service Monitoring (ISM) Non-Road Mobile Machinery (NRMM)
VCA does not require manufacturers to carry out GB ISM testing on the basis of having a provisional approval. NRMM’s are currently approved under the VCA’s GB Provisional Type Approval Scheme.
A GB Provisional Approval is not issued under Regulation (EU) 2016/1628; therefore, the provisional approval itself does not carry In-Service Monitoring (ISM) requirements. As GB Provisional Approvals are granted based on a valid EU 2016/1628 approval, the engine or engine family remains within the EU scope for ISM.
VCA ISC Annual Report Reports