In the wake of the Dieselgate scandal, various car manufacturers have come under scrutiny for their vehicles’ emissions. And, along with Mercedes, Nissan Renault and Peugeot Citroen, Ford will face legal action in the UK for alleged emissions cheating later this year.  

The emissions claims centre on the use of illegal defeat devices. A defeat device is any technology – whether hardware or software – that manipulates emissions control systems in vehicles to cheat regulatory tests. These devices allow cars to pass emissions testing under controlled conditions, while emitting far higher levels of pollutants under real-world driving conditions. 

Defeat devices are illegal because they deliberately mislead regulators and consumers. In the EU, UK, and US, car manufacturers must certify their vehicles comply with emissions standards under normal driving conditions, not just in lab tests. 

But Ford claims it never used defeat devices – so why is it included in the Dieselgate claims?  

Ford’s ‘thermal window’ software defence  

‘Thermal window’ software is designed to deactivate a vehicle’s emissions control systems under specific environmental conditions, such as extreme temperatures or altitudes. Manufacturers, including Ford, have argued this mechanism is necessary to protect engines from potential damage and ensure safe operation. However, this deactivation can lead to increased emissions of pollutants like nitrogen oxides (NOx) during normal driving conditions. 

Ford has consistently maintained it did not employ illegal defeat devices in its vehicles. The company asserts its ‘thermal window’ software is a legitimate measure to safeguard engine integrity and does not constitute an unlawful attempt to manipulate emissions testing results. But a leading court delivered a blow to Ford’s claims.  

European Court of Justice ruling: What it meant for Ford emission claims 

In 2020, the European Court of Justice (ECJ) delivered a landmark ruling on the legality of ‘thermal window’ software. The court concluded such software does qualify as a defeat device under EU law and is only permissible when it protects the engine against sudden and extraordinary damage. The ruling emphasised using these devices under normal driving conditions – which are common in the EU – is unlawful. 

The ECJ’s decision had significant implications for manufacturers using the ‘thermal window’ defence. For Ford, this ruling could significantly harm its stance in the ongoing legal proceedings.​ 

What should Ford diesel drivers do now?  

If your Ford diesel vehicle contained ‘thermal window’ software, you could be due compensation. This is because you may have:  

• Overpaid for a car that doesn’t meet environmental claims. 
• Experienced increased maintenance and running costs. 

Many drivers affected by the Dieselgate scandal have received payouts – so if you’ve owned or leased a Ford diesel car from 2009 to 2018, it’s worth checking if you’re eligible to join a claim.  

In similar cases involving Volkswagen, UK claimants received payouts averaging £2,120 and Ford drivers could be next.