LED bulb problems and how to fix them

Most switches to LED go smoothly. But cars differ, and some problems come up more often than others. Here are the most common, and what to do about them.

The car shows a bulb warning

Many newer cars check the current in each bulb. An LED bulb draws less current than halogen, so the car may think the bulb has failed. Choose a bulb with built-in CAN bus, such as Luxtar Hero or Premium Canbus, and most cars will not show the warning. If you still get one, or use a bulb without CAN bus such as Onyx, a CAN bus resistor or CAN bus adapter fixes it.

The bulb flickers

Some cars drive the lights with fast current pulses instead of a steady current. Halogen does not notice, but an LED bulb may flicker. A CAN bus adapter between the bulb and the car connector gives the bulb a steady current and removes the flicker.

One bulb does not light

An LED bulb has a plus and a minus, unlike halogen. If it does not light, turn the connector half a turn and try again. If it still does not light, try the bulb on the other side to see whether the fault follows the bulb or stays in the car.

The bulb does not fit or the dust cap will not close

LED bulbs have a heat sink or fan behind the socket and are therefore longer than halogen. Measure the space behind the headlight before you buy. If the cap will not close, extended dust caps are available. Never drive with an open headlight, moisture and dirt ruin both bulb and reflector.

Wrong beam pattern or glare

The LED chips should face the sides, at three and nine o clock, just like the filament in a halogen bulb. If the bulb is twisted the beam becomes uneven and can dazzle. Turn the bulb in the socket and check the light against a wall. Always do the same on both sides.

A faint humming sound

Many LED bulbs have a small fan that cools the bulb. A faint hum when the light is on is normal.

Still having problems?

Contact us with your car model and year and we will help you. You have a 30-day open purchase if the bulb does not fit.

Find the right bulb for your socket: H7, H4 and H1.

Also read How to fit LED bulbs and LED bulbs compared with halogen.

Not sure which bulb to choose? Read Best low beam and high beam bulbs 2026, where we compare Hero, Premium Canbus, Osram Night Breaker LED and more.