This article is more than 1 year old

This article is more than 1 year old

The US Department of Justice has launched a criminal investigation into Ford’s emissions certification process.

Ford said on Friday it was fully cooperating with government agencies, as it became the latest car manufacturer to be investigated over emissions.

However, Ford said the concerns did not involve the use of defeat devices – the cheat software used to deliberately lower emissions during official tests, which were at the heart of the Volkswagen “dieselgate” scandal in 2015.

According to a regulatory filing by Ford, the company voluntarily disclosed what it called a “potential concern” to the US Environmental Protection Agency (EPA) and California’s Air Resources Board two months ago. Ford said in February it had hired external experts to check its testing procedures after its employees raised concerns.

The focus of thinvestigation appears to be whether Ford accurately assessed the “road load”, or drag and resistance, of its vehicles, and its “coast down” testing, when a vehicle stops once power is no longer applied.

The modelling can significantly alter the certified emissions: a report by the International Council on Clean Transportation in 2016 found that in every model it analysed manufacturers were underplaying road load figures and subsequent carbon emissions by an average of 7%.

Even if the discrepancy is far lower than from defeat devices, Ford could be fined. It said: “Because this matter is still in the preliminary stages, we cannot predict the outcome and we cannot provide assurance that it will not have a material adverse effect on us.”

Mercedes and its parent company Daimler remain under investigation in the US by the DoJ and EPA for possible defeat devices in Mercedes diesel vehicles, in a process that has lasted nearly three years.

Lawyers have filed a class action on behalf of Mercedes car owners in the US courts, claiming that vehicles marketed as eco-friendly were instead significantly exceeding pollution limits.

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The EPA said earlier this month that more legal actions against car manufacturers were “in the works”. In January, Fiat Chrysler reached an $800m settlement with the US government and California to resolve claims of defeat devices in its vehicles.

Independent, real-world emissions tests have shown that diesel cars from virtually all manufacturers significantly exceeded official NOx pollution limits.

VW admitted installing defeat devices to game the testing system in 11m cars it produced. In the US, It has agreed to pay more than $25bn in fines, compensation and buyback settlements with owners.