The Driver Vehicle Standards Agency (DVSA) has reclassified the inspection and rework programme following a number of fires in Vauxhall Zafiras as an official safety recall.

It has acknowledged that the root cause of the fires was improper repair of the thermal fuse of the resistor in the heating and ventilation system, undertaken outside Vauxhall’s authorised service and maintenance processes and schedule.

The rework replaces the resistor pack and other faulty components and returns the heating and ventilation system to its original design condition.

“We recognise that owners may have vehicles which have been improperly repaired without their knowledge or before they bought the vehicle,” said Rory Harvey, chairman of Vauxhall Motors.

“Safety is our priority and we have been working tirelessly in the past weeks to find the root cause and contact owners to explain the situation and our actions.

"The DVSA’s acknowledgement of the root cause is an important milestone but the important thing now is to ensure that all Zafira B owners bring their vehicles in for inspection and rework.”

All 234,938 Vauxhall Zafira B owners have been contacted by letter to inform them of the issue and explain how they can remain safe pending inspection.

To date, Vauxhall dealers have inspected and repaired more than 45,000 vehicles.

The goal is to have all vehicles inspected within a 10- to 12-week time span.

While owners wait to be asked to arrange an appointment, Vauxhall has written to them all with the following advice: "If you are the first owner of your Zafira B and your heating and ventilation system is functioning well, and your car has never been subject to any repair in this area, there is no risk of a fire.

"If you are not the first owner or you have had repairs in this area you should set your fan speed to zero (0) on the heating and ventilation system.

"If necessary, you should use fan speed four (4) only for the time needed to demist the windscreen. Please continue to follow this advice until your vehicle has been inspected."

When owners bring their vehicles in to a retailer, Vauxhall technicians will inspect the heating and ventilation system on each vehicle and, as a precautionary measure, replace the resistor in every vehicle.

This is because it is not always possible to detect an improperly repaired resistor without extensive examination of the part.

In addition, the retailer will also test the performance of the blower motor, inspect the wiring harness and the pollen filter to ensure they have no damage and are in good condition.

As a matter of extra caution, it will also install additional water protection below the windscreen scuttle panel to minimise any opportunities for water ingress following improper refitting after removal.

This work is being carried out free of charge.