Why Do My Headlights Flicker? (7 Causes & Solutions) - Vehicle Freak

• Emma Davies

Updated on August 19, 2022

Driving with decreased or limited visibility is more than just a scary scenario to be in, it is also highly dangerous. Sometimes this issue can be easily fixed at home and be a preventative measure for any further damage, but it might also need some work if it’s more complex.

If you’re wondering why your headlights flicker then the answer might be more obvious than you realize, or it could indicate an issue with your alternator, connectors or fuses, overstressed wiring, or a weak battery.

Why Do My Headlights Flicker?

A flickering headlight would most commonly be blamed on a faulty or dying headlight bulb, and although this can be the cause, it can also be a way to recognize other problems in your vehicle before they become too serious.

Another way to help you identify the cause of your headlight’s flicker is to pay attention to the pattern your lights flicker in, and if certain factors trigger them to start flickering.

Causes of Headlight Flickering

Let’s take a closer look at the 6 causes of headlight flickering before we get into the best solutions for the job.

1. Weak Battery

Your headlights rely directly on power from your battery to function, which is why flickering, dimming, or failing headlights are common signs of your battery dying.

The average car battery will last anywhere from three to five years but this depends on how well you look after your vehicle, or if you live in a hot or cold climate this can also impact its lifespan.

Even if your battery isn’t to blame, a flickering headlight can still be a sign of a fault within your electric system and this can also illuminate your battery warning light.

2. Alternator

When your alternator isn’t able to charge your battery then this will affect your electrical output, which can result in flickering, dimming, or completely inoperable lights.

As your alternator is no longer fully functioning, it won’t be able to charge your battery which means your battery’s existing charge will be quickly drained by your headlights and other electrical systems.

Usually, a faulty or completely busted alternator will illuminate the battery light on your dashboard.

3. Loose Fuses or Connectors

A loose connection or fuse that isn’t properly seated can cause your headlights to flicker without proper contact, but this can be tricky to locate.

You can usually spot a loose fuse or connector easily as your headlights will flicker more on rough road surfaces where the connectors or fuses are not able to make a proper connection to their seat and disrupt the electrical flow.

4. Bad Bulbs

If you notice your fuses are all correctly fitted and your battery has no faults then it could just be as simple as a worn-out bulb or lamp that needs replacing. This is the quickest and easiest fix for all the possible reasons why your headlights flicker.

5. Incorrect Wires

Bad wiring can be caused by physical damage to the headlight component or melting from inside the connector. Sometimes the wire might start to pull out the rear of the connector which can create a poor connection.

You can find out more about the Symptoms of Loose Battery Cables here.

6. Internal Communication Faults

A faulty headlamp switch can create a disruption in the communication made between the electrical system and the computer system which can create flickering.

You may need to look deep into the computer and electrical systems such as the relays, fuses, battery, alternator, and switches.

7. Car Accessories

If you have installed a large stereo system or have other electrical accessories connected to your car then you might want to check that they are not having a direct effect on your headlight’s performance.

Strong bass hits from a stereo system can create a dimming response from your headlights and this could create flickering headlights. You might also find that several faults from other components will create an excessive current draw as components build up heat, and shut off as internal resistance overcomes the power input.

Flickering Headlight Solutions

Diagnosing any issue can be difficult if you don’t know where to start looking, but there are a few obvious checks you can make to inspect for physical damage to parts of the headlights and electrical systems.

More complex issues may require a trip to a mechanic to fix as your electrical system is not something you want to get wrong if you don’t feel fully confident in taking on this task.

1. Bulb Replacement

The easiest solution for flickering headlights is to unscrew your headlight protection cover and inspect the bulbs to see if you can once any damage or discoloration. Your bulbs should fit well into their seat and not wobble or feel loose.

2. Check Battery

Performing a quick battery health check at home is an easy way to get a good assessment of your battery’s health and can help you work out if a new one might be needed.

Visual assessment of your battery will be the easiest to carry out, check to see your battery is clean and dry with no grime building up around the screws, clamps, and terminals.

Check for any loose connections or damaged wires, and if these all seem okay then you will need to check the battery’s state of charge. If your battery has grime build-up then you can clean this away to see if there are improvements, if not then a battery replacement might be needed.

3. Check Alternator

If your battery light is illuminated then this might be pointing you in the direction of your alternator. To check your alternator you can start your engine and remove the negative cable from the battery, if your vehicle stalls or died then this means your alternator is in need of a replacement.

Replacing and fixing an alternator is a job that should only be taken on by a trained mechanic. It will take around 2 to 3 hours to complete and costs anywhere from $100 to $350 for an aftermarket or new OEM alternator.

4. Inspect Wire Fusing Panel

Checking for wiring issues under the hood is usually straightforward as any breakages or kinks in the wires will be easy to notice. Check the wires in the fuse panel behind the steering wheel column on the driver’s side for damage as well.

If you do notice any damage to the wire fusing panel then you should ask a mechanic for more help as trying to fix electrical wires yourself is a dangerous business.

5. Unplugging Accessories

If you have an older vehicle then the chances are you’re missing out on the latest technology and infotainment systems such as Apple CarPlay and Android Auto.

You might be connecting your own gadgets or dongles to try and get this technology in your vehicle, or just simply overloading your vehicle’s electrical system with too many draining devices.

Whatever the cause, you might find unplugging accessories such as phone chargers or other gadgets will help reduce the amount of excess power being drawn from your car which might result in your flickering headlights.

FAQs

How do I stop my headlights from flickering?

The easiest way you can try to stop your headlights from flickering is to try changing the bulbs and see if this fixes the issue. If your current bulbs are wobbling at the touch then your might find the loose connection was to blame.

How do you know if you have a bad alternator?

A bad alternator will cause electrical faults in your vehicle such as dim or overly bright lights, battery warning lights, trouble starting or regular stalling, and malfunctioning accessories.

What causes the headlights to flicker?

Most commonly a dead or failing battery will cause your headlights to flicker as they are not getting enough power to keep them running well.

Would a bad alternator cause lights to flicker?

When the alternator is not working then this will affect all your vehicle’s electronics, including flickering dash lights.

Conclusion

Flickering headlights are usually related to an issue within your vehicle’s electrical components which can often be located through visual inspection or by testing your battery voltage.

You can figure out why your headlights are flickering by checking over the condition of your vehicle’s alternator, and electrical wirings, or see if the connections are loose in your bulbs.

By readjusting your bulbs you might find this fixes any loose connections in your vehicle, or helps you to spot a more important issue such as a failing battery or alternator.

Here are some other articles to read:

Why Are My Car Headlights Not Bright Enough?

H11 vs 9005: Headlight Bulb Differences

How to Fix a Cracked or Broken Headlight