Volkswagen is to provide a two year guarantee for the cars in Europe fitted with emissions cheating devices which it agreed to modify.
A number of UK consumers have complained that the modifications have affected performance and reliability.
The two year guarantee will cover exhaust and emissions control parts.
The European Commission has been putting pressure on VW to compensate customers over its emissions scandal, but the company has refused.
And European class action lawsuits are picking up steam.
Analysis: BBC business correspondent Theo Leggett
Volkswagen’s “fix” was meant to solve one big problem – but has it created others?
There are plenty of owners who think it has. There have been widespread reports of expensive mechanical failures, of cars losing performance, becoming less economical and – somewhat ironically – producing excessive exhaust fumes.
Volkswagen itself argues that 99% of owners haven’t complained. That may be true, but given the huge numbers involved, that still leaves thousands of unhappy customers.
The company is under intense political pressure in Europe to do more for customers affected by the scandal.
In the US, it is being forced to pay out billions of dollars to buy back affected vehicles and provide compensation. But owners in Europe haven’t received a penny, because the company believes that the value of their cars hasn’t been affected.
Under those circumstances, it could ill-afford another public-relations disaster. There’s no question that the chorus of complaints has been growing in recent weeks – and attracting media attention.
Its new “trust building measure” may help to mollify some of those angry owners and limit negative press coverage. But pressure from consumer bodies for a more generous response is unlikely to ease.
The guarantee has conditions attached.
It will only cover certain car parts in vehicles that have been driven for under 250,000km (about 155,000 miles), and will depend on the service history of the car and the age of the affected parts.
VW admitted to US regulators in September 2015 that it had cheated on emissions tests there using software installed in as many as 11 million diesel vehicles sold worldwide – the majority of them in Europe.
In the aftermath of the diesel emissions scandal, Volkswagen agreed to modify millions of vehicles in Europe which were equipped with the software capable of undermining the emissions testing process.
In the US the company agreed to pay substantial compensation and buy back cars.
However, emissions controls are not as tight in Europe, and the firm has resisted paying compensation, despite pressure from the European Commission.
But on Tuesday UK law firm Harcus Sinclair and Dutch Foundation “Stichting Volkswagen Car Claim”, a US-style class action on behalf of an estimated 180,000 Dutch VW car owners, teamed up in a move for coordinated litigation.