A Morrisons supermarket In Wrexham was forced to close its petrol station after fuel became contaminated with water, leading to breakdowns on the forecourt.
A number of cars ground to a halt immediately after being refuelled on Wednesday, due to the tainted petrol, and roadside assistance vans were called to help motorists get on their way.
Morrisons has since announced that it has launched an inquiry into why its warning system, which normally alerts petrol station operators to pollutants in fuel, failed.
The supermarket has also confirmed that motorists who have been affected would be compensated for any damage caused to their cars.
Speaking to the BBC, a spokesman for Morrisons said: "The recent bad weather caused some water, only a small amount, to get into the tanks.
"The sensors went off but about a dozen had got fuel. Yesterday we shut the pump down, drained the tank and flushed the system and refuelled."
He went on to say that the supermarket's insurers would contact those affected, and when asked whether motorists could expect to be reimbursed, said: "I'm guessing that's what will happen."
Sainsbury's, Asda and Tesco were forced to follow suit.