The Consumer Rights Act 2015 gives you the right to take action up to six years (or five in Scotland): www.honestjohn.co.uk/problems-with-a-new-or-used-c...s

However, making a claim on a car that's almost five years old will be difficult. You will need to prove the failure is due to a fault and not wear and tear. This means spending money on an independent mechanical inspection and legal advice, with no guarantee of a positive result.