On Thursday, Ford announced a recall affecting almost 1.3 million cars in the US. It covers the 2012-2018 model year Ford Focus; specifically those with either a 2.0L GDI engine built before April 13, 2017, or those with a 2.0L GTDI engine built before February 2, 2018. A further 136,272 vehicles are affected in Canada, with 44,521 more in Mexico.

The problem is with the evaporation system fitted to the cars’ fuel tanks. The affected cars have canister purge valves that can refuse to close, which in turn could cause enough vacuum within the tank to deform it. Ford says that the concern is that cars could refuse to start or stall while driving refuse, and then refuse to restart. Affected vehicles may display a malfunction indicator light, or maybe just a fluctuating fuel gauge.

The fix sounds relatively simple: a reprogrammed control module that detects if the purge valve is malfunctioning and prevents the above from happening. Ford dealers will also inspect and replace affected fuel systems if necessary.