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You open your mailbox and see it sitting there: a letter from the manufacturer stating that your vehicle has been recalled. Receiving a recall notice for a seemingly minor matter may not crack your to-do list immediately, but small problems can have outsized consequences. That’s why you shouldn’t delay taking your car back to the dealership when you’re notified of a problem.

Even if the reason for a product recall seems trivial, note that even minor issues can lead to accidents and fatalities. In 1996, Ford recalled 8.7 million Ford Explorers, Broncos, F-Series pickup trucks, and Lincoln Town Cars to fix an inexpensive problem with a small electronic switch used to deactivate the cruise control function. Many people ignored the recall notice, assuming that they could drive their cars safely as long as they didn’t use cruise control.However, the glitch overheated some Fords, even when parked, and started several fires that spread through garages and houses. The ostensibly insignificant problem not only cost the company hundreds of millions of dollars; it also took several lives.

If it seems that cars have more safety issues than ever, it’s not your imagination. The federal government issued a record number of recalls in 2015: 900 separate incidents affecting 51 million vehicles nationwide. Some of them, for issues such as faulty airbags and ignition switches, did not seem pressing to owners at the time but caused widespread damage, including several dozen deaths.

[Read Our Takata Recall Guide for Honda Owners]

Most notably, nearly two dozen automakers in the U.S. recalled about 70 million vehicles for faulty airbags from Japanese supplier Takata. The ever-expanding recall was issued after a report stated that the air bag inflators could rupture in high temperatures, sending metal fragments to strike the driver and passengers. It is estimated that the defect killed at least 10 people and injured dozens of others.

Shortly after the Takata recalls began, it was discovered that General Motors had been hiding reports for several years that the ignition switch in many of its small sedans, including the Chevrolet Cobalt, Pontiac G5, and Saturn Ion, could slip into accessory mode without warning. The glitch shut down the engine abruptly, making the cars stop short at high speeds and cause collisions. That defect led to several hundred deaths and injuries.

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Though it didn’t endanger owners, Volkswagen was forced to recall more than half a million diesel vehicles in the U.S. last fall after it was discovered that the company cheated on emissions tests and that its cars didn’t achieve the stellar fuel economy advertised. Volkswagen is expected to pay a $14.7 billion settlement in connection with the damages.That’s several times more than GM’s $2 billion settlement for not acting sooner on reports of its defective ignition switches, and the $1.3 billion Toyota paid in connection with the sudden acceleration of its cars.

As the number of recalls expands and 10-figure civil penalties no longer astound, the ubiquitous headlines warning of vehicle dangers tend to reduce public sensitivity to the risks of leaving them unfixed. “With so many products being recalled, especially in the automobile industry, consumers are often bombarded by product recall announcements, leading to recall fatigue, which results in consumers ignoring important recall information,” said Kaitlin Wowak, an assistant professor at the University of Notre Dame’s Mendoza College of Business studying supply chain management. “Consequently, when consumers get recall notices in the mail that their car is being recalled, it is very likely that they will ignore the notice, thinking that it doesn’t apply to them or the problem is not serious enough to warrant their time and attention.”

[Read About the Biggest Car Recalls in History]

The government is taking steps to reduce the number of fatalities and injuries from vehicle defects. Last year, Congress granted the National Highway Traffic Safety Administration stronger enforcement powers, allowing the federal agency to levy civil penalties on automakers that fail to notify customers of safety defects in a timely manner. In 2015, it issued a $70 million civil penalty to Fiat Chrysler for failing to report legally required safety data, which delayed several important recalls. BMW received a $40 million civil penalty after failing to notify owners that certain MINI Cooper models didn’t meet the minimum standards for side-impact crash protection.

“The record recalls over the last two years demonstrate NHTSA’s emphasis on proactive efforts to get ahead of safety problems,” said NHTSA Communications Director Bryan Thomas.

Earlier this year, the Department of Transportation reached an agreement with 18 automakers to collect information on safety defects more efficiently. The collaboration – the first of its kind in the automotive industry – is similar to how the Federal Aviation Administration works with airlines to share safety data.