What Happens If You Hit A Car's Power Button While Driving At Speed?

While sitting in slow-moving traffic during the morning commute or midway through a particularly dull highway drive, you might have wondered what would happen if you pressed your car's engine start button. Would the car's engine cut out altogether? Would you see a slew of warnings pop up on the dash? Or would it simply do nothing? Depending on the car you drive and exactly how you push the button, the answer could be all of the above. The exact effect of pushing the power button will vary based on the safety systems implemented by your car's manufacturer, and it's best not to try to find out the answer yourself if you're on a public road. 

Nonetheless, various drivers have tried it out for themselves, including a tester at TFLCar. The driver pushed the stop button once on their Honda Ridgeline pickup, and the engine didn't shut off, although a warning appeared on the instrument cluster and the button's backlight began to blink. Pushing and holding the button for a couple of seconds did shut the engine off, leaving the instrument cluster blank. The power steering and brake assist were also disabled, although both the brakes and steering were still functional. Other testers have confirmed that pushing and holding the button leads to a similar result in cars from Volvo and Jaguar. In both of these cases, the testers could also restart the car's engine by pushing the button again.

The testers who were driving the Volvo and Jaguar noted that the car's transmission defaulted to neutral when the button was held to turn the car off. Both testers were able to restart their car by pushing the button and shifting back to drive, without any obvious lasting effects. It's still not a good idea to try it for yourself, though, since not everyone who tested out the feature has gotten away scot-free.

YouTuber George Austers attempted the same trick with a BMW 5 Series, and although the car stopped when the engine start button was pressed, it displayed an error code when he restarted it. The code and its associated dashboard warning light remained active after he restarted the car several more times. Unlike the other testers, Austers didn't have to hold down the button to turn off the engine; instead, he pressed it three times.

In any case, it's safe to assume that if you accidentally press the engine start button while you're driving along, you probably won't suddenly lose power or damage the car, regardless of the type of car you drive. Manufacturers accommodate these kinds of accidental presses, but holding down or repeatedly pressing the button can act as a "kill switch" feature to stop the engine in an emergency. If you haven't already, it's worth checking if there are any other features that you didn't know your car had, since there might be more than you think.