8 Reasons Why Hazard Lights Blinking When the Car Is Off

Hazard lights are useful for warning other drivers about road hazards such as accidents, bad weather, emergency vehicles, issues with your vehicle, etc. But it can be distressing when your car’s hazard lights stay on even after switching off the engine.

Why are hazard lights flashing when the car is off?

Door Issues

The hazard lights can stay on if one or more car doors are not properly locked. This is prompted by the car sensor that alerts you about opening car doors. You can easily diagnose this by closing all the doors well; if the lights turn off, it means the door hinges are defective and need fixing.

A Robust Security System

Some cars feature robust anti-theft systems that require you to follow precise guidelines to turn them off. You might need to read the owner’s manual/handbook to learn how to turn off the warning lights. For instance, the BMW key may have an integrated alarm system that must be connected to the vehicle to turn off the warning lights.

Additionally, you may need to insert the car key into the driver’s door and leave it there for a specified time to turn off the hazard lights. Furthermore, a third-party anti-theft device may cause the hazard lights to stop working. The car electrical technician might have crossed the wires while installing it. In that case, the hazard lights will stay on even after you turn off the car.

Take your car back to the technician so they can monitor their work and correct the issue.

A Defective Hazard Switch

A broken hazard switch is the most common cause of hazard lights staying on after turning off your car. The hazard button can get stuck in the “on” position causing the lights to remain on even after you turn off the engine. This issue and defective electrical relays affect all car models, but some car models are more susceptible to it than others.

You can fix the problem by repairing or replacing the damaged components. When you press the hazard button, see if the hazard lights turn on and off and if the glow is consistent. To resolve this issue, shake or toggle the hazard button until it releases. Spray some WD-40 on the hazard button if this doesn’t work. The solution should lubricate it and clear out any dirt or surplus moisture.

If the issue persists, it might be better to take your car to a qualified repair.

Malfunctioned Sensor

Most contemporary cars feature sensors that warn you anytime someone tries to steal it or kicks in your door. Usually, these sensors are connected to the hazard lights, and the light and horn are activated when the doors open without turning off the sensor. Occasionally, the sensor develops a defect and sends signals to the hazard lights causing them to stay on even when you press the switch-off button.

You can install a new sensor or temporarily disconnect the hazard lights from the faulty sensor until you can fix them.

Minor Corrosion of Electrical Parts 

Malfunctioning hazard lights may be a symptom of corrosion in one of the sockets. Corrosion may build up on the electrical parts over time, especially in high humidity or rainy and cool climates. Fixing the issue requires physical inspection and technical expertise. Begin by checking the hazard light’s connection points under the hood for signs of corrosion.

Also, inspect the fuse box and hazard switch for rust because corrosion in any of these components will need a thorough cleaning. The good news is that there are cleaning products specifically for this use that quicken the cleaning. They also restore the function of the electrical parts.

Electrical Short

A shortened turn signal can make the hazard lights not go off. It happens when the circuit board or relay system has an internal fault. The relay system has a resistor that causes the hazard lights the rhythmic blinking. The hazard lights may blink abnormally if the relay system develops a problem. A shortened turn signal or a defective hazard switch can cause the relay to malfunction.

The flaw might make the hazard lights blink all night, consuming battery power. An electrical short can cause the hazard lights to turn on and flash at an abnormal speed. You must unplug the switch to determine if the problem stems from the relay: do the hazard lights go off? A voltmeter also helps to see if there is a voltage drop while your automobile is idling.

A voltage drop may occur due to grounding faults within the relay system when the hazard lights blink without command. A certified car electrician or mechanic can fix this problem.

Glovebox Issues

A sporadic connection problem in the glovebox may cause the hazard lights to stay on even after you turn off the engine. In most modern cars, the glovebox has a relay system that, when opened, illuminates the interior and, when closed, turns the light off. Most modern automakers connect the hazard and the glovebox lights to the same wiring system.

So, even after you switch off the car, the warning lights might not turn off if the glovebox is unfastened or unlocked. The electrical relay system may develop flaws or malfunctions affecting the glovebox light and other lights attached to it, including the hazard lights. A certified mechanic can inspect and repair the wiring system.

An Earthing problem

An earth issue can cause the hazard lights to stay on after washing the car or when you drive in the rain. Earthing can complete the circuit and let power through even with the switch turned off. Some vehicles, such as the Mercedes Benz Kompressor, may experience earth issues during rainy seasons.

You can quickly fix this issue by spraying Water Displacement, 40th formula (WD-40) on the hazard switch and electrical relays. The spray acts as a lubricant, rust preventative, penetrant, and moisture displacer. WD-40 can displace moisture and eradicate earthing problems.


Hazard lights that won’t stop blinking even when your car is off are inconvenient. They drain the vehicle’s battery. So, you will have to disconnect the battery every time you park.

But that inconvenience pales in contrast to the possible electrical system problems. If you fail to address this issue quickly, there could be adverse effects. These lights can cause your battery to drain faster than usual. With time, they could ruin the battery. So, you will have to replace the battery. Don’t procrastinate! Get a certified technician to address the problem.