Kia
Kia and Hyundai haven't had the best track record recently in terms of overall reliability. From interior elements falling off to electrical shorts causing fires (the latter problem affecting some 3.3 million vehicles), the 2020s have not been particularly kind to Hyundai and its subsidiary. Because Kia shares much of its parts with its parent company — think Ford and Lincoln, for example — when one suffers from such failures, often the other does as well, boosting the numbers deep into the six figures. Such is the case with this latest recall, affecting both manufacturers equally, and just as catastrophically: a defective purge control system check valve, which can lead to a melted fuel tank, according to the recall notice provided by the NHTSA (PDF). NHSTA shared a similar notice about affected Hyundais.
To clarify exactly what's meant by a "melted" fuel tank, it's like accidentally putting a plastic spoon next to a stove. The tank itself rests close to the affected vehicles' exhaust system, which gets scalding-hot when the car is running. When a material not designed to withstand elevated temperatures makes contact with a hot surface, it results in localized melting. The same phenomenon occurs with these cars, with a number of obvious risks ranging from fuel leaks to fires, something that's becoming alarmingly difficult to fight with electric car fires.
As for which cars are affected, the notice claims that it does not follow a regular VIN pattern, so all individuals who receive the notice or own vehicles in the specified production ranges and equipment packages should get theirs checked regardless. Moreover, if any leak is suspected, keep the car parked outside. Gasoline vapors are toxic and flammable.
What the actual problem is
Kia
The problem rests with the purge control system check valve, otherwise known as the purge valve. A purge valve is an emissions-control device, a valve connected to the car's charcoal canister. Basically, vapors from gasoline contain useful energy, so rather than letting it filter out into the atmosphere, there's a canister full of activated carbon connected to your car's fuel system. This absorbs the fuel vapors, which are then released in a moderated fashion by the purge valve into the engine's intake manifold, thus improving your car's efficiency and lowering harmful emissions.
A faulty purge valve, therefore, leads to an unregulated release of these vapors — vapors that are pressurized. Normally, this isn't an issue because the valve works with the engine's fuel pump, meaning the vapors are only directed one way. If the valve that controls the direction of these vapors deteriorates, the backpressure caused by the faulty valve will force the vapors back into the fuel tank, effectively "overfilling" it like overfilling a balloon.
This will expand the fuel tank until it contacts the exhaust pipe, thus burning a hole through the tank itself. Incidentally, this valve is also why you shouldn't top off your fuel tank — doing so may clog the valve, causing it to malfunction.
What can you do about it?
Hyundai
Of the roughly 330K vehicles affected, according to both reports, it's not within a specific VIN range but rather a specific production timeframe, so any Kia K5 or Hyundai Sonata in the production range is theoretically among those affected. Because it's a manufacturer's recall, it should come with little to no cost to the consumer.
If you, for whatever reason, didn't get a recall notice, according to the recall report, drivers should look out for a popping sound coming from the fuel tank (assumedly the fuel vapors escaping from holes, like popping open a soda can), a check-engine light, and/or the vehicle running rough. Gasoline vapors are instantly detectable by their smell. The vapor often causes certain ailments, such as headaches, nausea, and drowsiness, which can drastically impact a driver's capacity to maintain control. Moreover, the vapor is the flammable element of gasoline, not the liquid. While the liquid may be the substance leaking out, if the vapor comes into contact with a hot exhaust, it poses a serious risk of combustion.
In terms of prevention, if you even suspect your vehicle may be affected by this issue, it's likely a good idea to get the purge valve checked and/or replaced. It's a simple job requiring disconnecting some lines and electrical wiring, but it could potentially avert a far more catastrophic situation. Of course, the presence of gasoline vapors isn't the only telltale sign that your vehicle may catch fire. In fact, numerous other telltale signs exist — if your Hyundai or Kia exhibits any of these, always see a mechanic immediately.
