Why Are the Lights Flickering in My Car?

When your car’s lights stop working correctly, it can be dangerous, especially if you’re driving at night. That’s why it’s important to understand why it happens and what you can do about it. 

This guide covers all the possible reasons your car’s lights might be flickering. 

The lights flicker while my car is running

There are six possible reasons your car’s headlights are flickering while the engine is running. 

1. Failing battery

The most obvious explanation for lights that aren’t working correctly is a dying car battery. There are other symptoms to look out for, such as:

• Difficulty starting the engine

• Faulty electrics

• A dashboard warning light depicting a battery

Batteries die for various reasons, from corrosion to extreme weather conditions. It’s possible to recharge a car battery, but if it fails due to old age or wear and tear, you’ll have to replace it.

This guide explains the various options you have when your battery dies. There are also several things you can do to extend the life of your battery.

How much does it cost to fix a failing battery?

The average price of a battery replacement is £234.82.

2. Faulty alternator

The alternator in your car turns mechanical energy into electrical energy, charging the car battery as you drive and powering various components. Your battery could be in perfect working order, but if the alternator can’t charge it, you’ll quickly notice signs that something isn’t right.

The following symptoms indicate there may be a problem with your alternator:

• Flickering, dim or overly bright lights

• A dead battery

• Battery warning dashboard light

Alternators can sometimes be repaired, but it’s usually more cost-effective to replace them.

How much does it cost to fix an alternator?

An alternator repair costs £533.64 on average.

3. Loose connection/fuses

The flickering may be caused by a fuse that isn’t properly seated or a loose connection in the system. If this is the case, the flickering will probably be worse when driving on uneven road surfaces.

It can be challenging to locate loose connections for the untrained eye, so you may have to contact a mechanic.

How much does it cost to fix a loose connection?

The average price of an electrical fault diagnosis on FixMyCar is £71.40.

4. Worn bulbs

Light bulbs don’t last forever; as they age, they sometimes stop working correctly. The same applies if they are damaged. You’ll be pleased to know this problem is easy and cheap to fix - all you have to do is replace the bulbs.

You can fit new bulbs yourself, or, if you don’t feel confident, get a mechanic to do it for you.

5. Wiring issues

When various headlight components are damaged, it can cause flickering lights. For example, if the inside of the connector melts, it causes a poor connection to the bulb, making it come on intermittently. Wires can also work themselves loose at the back of the connector, creating the same results.

How much does it cost to fix wiring issues?

The average price of an electrical fault diagnosis on FixMyCar is £71.40.

6. Defective headlamp switch

The final explanation is that your headlamp switch is faulty, preventing the computer system from communicating with the electrical system. Sometimes, this can be fixed by replacing the headlamp switch - usually in older or high-mileage vehicles - while a deep dive into the electrical or computer system is required at other times, particularly in newer cars.

The dashboard lights flicker and my car won’t start

These symptoms typically indicate one problem, as discussed below.

Bad ignition switch

The ignition switch connects the circuit that provides voltage for the starter motor and creates the right conditions for the engine to crank. When it fails due to damage or old age, your car will struggle to start.

Other symptoms of a bad ignition switch are:

• Car starts suddenly, then stalls

• Car stalls while driving

• Problems turning or removing the key

• Engine won’t crank

• Electrical issues (such as flickering lights)

A bad ignition switch can have many causes, such as corroded terminals, loose connections, bad wiring and electrical surges. That’s why getting a mechanic to investigate and provide an accurate quote is a good idea.

Read this guide for more advice on diagnosing and fixing common car problems.

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