When only your high beams work, the most common culprit is burned-out low beam filaments. However, because high and low beams use different circuits, the issue could also be a blown fuse, a bad relay, a worn-out switch, or melted wiring.
When your high beams work but your low beams do not, it usually means the low-beam filament has burned out, the headlight relay is failing, or the circuit's fuse has blown.
Your headlights only working on high beams usually points to a few common electrical or hardware issues, the most likely being burnt-out low beam filaments in dual-filament bulbs, a faulty headlight relay, or a bad dimmer switch.
Headlights are typically stuck on high beam due to a faulty headlight/dimmer switch, a stuck relay, or a wiring short. Other common causes include a broken dual-filament bulb creating a short or a malfunctioning automatic high-beam sensor.
When one headlight is out but the high beam still works, the most common culprit is a burned-out low-beam filament in your bulb. Most vehicle headlights use dual-filament bulbs (a single bulb that handles both low and high beams). If only the low beam fails, the high beam will continue to work.
To reset a headlight, the steps depend on what you are trying to fix. If your goal is to reset the aim/angle of your headlights, clear a dashboard error light, or restore clarity to a foggy lens, follow the specific steps for your situation below:
A blown (or failing) headlight relay generally exhibits clear warning signs, such as headlights that stop turning on, stay on continuously, or flicker while you drive.
A headlight relay replacement costs between $50 and $120 in total. The part itself is generally inexpensive, ranging from $15 to $40, while professional labor typically adds another $35 to $80 for the quick 15-to-30-minute installation.
AutoZone employees may install your headlight bulb if you purchase the bulb at their store and it is a quick, straightforward replacement. However, this is a courtesy service and is not guaranteed; it depends on store staffing, how busy they are, and the difficulty level of your specific vehicle.
To fix low beam headlights that aren't working, start by replacing the bulbs, as they are the most common point of failure. If the problem persists, check the dedicated fuses and relays, inspect the wiring and socket connectors for corrosion, and test the headlight switch.
A failing headlight ballast—typically found in Xenon HID or advanced LED systems—often causes flickering, dimming, or complete light failure. Because diagnosing electrical components requires bypassing the most common failure point (the bulb), perform the following steps to isolate the problem.
WD-40 can make cloudy headlights look instantly clear, but it is purely a temporary cosmetic trick. The oily formula fills in microscopic surface scratches and masks dullness. However, it does not fix the underlying oxidation and will wash away, usually lasting only a few days to a few weeks.
Yes, a blown fuse can absolutely affect only one headlight. In fact, many modern vehicles use independent fuses for the left and right sides, and separate fuses for high beams and low beams.
When your headlights suddenly fail, turn on your hazard lights immediately to alert other traffic, ease your foot off the accelerator, and gradually slow down. Do not hit your brakes abruptly. Carefully navigate to the right shoulder or the nearest safe exit.
Fixing a headlight electrical issue costs between $150 and $600 on average, including parts and labor. Your exact total will depend on the repair needed:
Yes, your car almost certainly has fuses (and relays) dedicated to the high beams. Typically, you will find either a single fuse for both high beams, or separate fuses for the left and right sides. Most systems also use a high-beam relay to handle the electrical load.
Yes, O'Reilly Auto Parts offers free headlight bulb installation, but only if you purchase the replacement bulb in-store. Keep in mind this service is at the discretion of the staff and is only available for vehicles with easily accessible bulbs.
AutoZone does not charge a labor fee for replacing headlight bulbs if you purchase the bulb in-store. You will only pay the cost of the new bulb, which ranges from $20 to $100+ per bulb depending on your vehicle.
AutoZone employees will walk outside with you and visually check if your headlight is burnt out. While they do not provide formal installation services, a store associate may occasionally offer to help you replace the bulb as a courtesy, provided the vehicle doesn't require removing parts like the battery or bumper.
To quickly tell if your headlight relay is bad, turn on your headlights and listen closely for a distinct "click" coming from the relay or fuse box. A silent relay or headlights that completely fail usually point to a dead relay, while flickering, dim lights, or lights that won't turn off can also indicate internal contact failure.
Headlight relays are typically located in the Power Distribution Box (fuse box) under the vehicle's hood. However, some vehicle models place them in the interior fuse panel near the driver's left kick panel or underneath the dashboard.
To check if your headlight switch is bad, first check for blown fuses or a clicking relay. Turn on the switch and test for voltage at its output terminal. If the switch receives power but none comes out when turned on, the switch is faulty and needs to be replaced.
To remove a headlight relay, locate the fuse box (usually under the hood), identify the relay using the cover diagram, and pull it straight out, using needle-nose pliers if necessary. Ensure the car is off, replace it with an identical part, and consider using electronic cleaner on the contacts.
To test a relay, you can use a multimeter and a 9V or 12V battery. First, test the internal coil's resistance to ensure it isn't fried. Then, apply power to see if the internal switch properly "clicks" and completes the circuit.
Yes, in many vehicles, a single relay controls both headlights. Often, you will have one relay for the low beams and a separate relay for the high beams. However, many modern or modified setups use separate, individual relays for the left and right headlights.