Tesco has apologised to customers after diesel was put in the petrol tanks at a garage in Catterick Garrison.
It meant customers unknowingly filled up filled up with the wrong fuel.
Tesco has blamed the mistake on human error and says only a small number of cars will have been affected.
– David Nieber, Tesco
"There has been an isolated incident where a small number of customers received the wrong grade of fuel when filling up at our store. We are in contact with customers affected to apologise and arrange any necessary repairs to their vehicles."