DIY replacement of light bulbs in the car – Ultimate guide for dummies!

DIY replacement of light bulbs in the car - Ultimate guide for dummies!

Not all defects or malfunctions need a visit to the garage. Depending on car model, several problems can be solved by the car owner himself. This applies to many cars with a failing light bulb. Read the detailed DIY manual for replacing filament lamps in your car. We remind you, that in some cars this is not as easy as it used to be.

Lamps and illumination in the car

Lamps and illumination in the carFirst of all, you need to determine which lighting technology applies in the car that needs its light bulb replaced, and which lamps are used.

In a car the following lamps can be distinguished:

– light bulbs (with a filament)
– xenon and bi-xenon (gas-discharge lamps)
– LEDs

1. Replacement of xenon lights

Replacement of xenon lights in the carXenon is used for the headlight (bi-xenon) and dipped beam. It gradually replaced the halogen lamps during the 90ies, although it nowadays represents an extra feature to an additional price for many car models. Therefore a specific model does not necessarily need xenon headlights.

The law dictates certain conditions for xenon lights such as automatic and stepless headlight levelling adjustment. A headlight cleaning system is required as well. For the gas in the xenon light tube to ignite, an electronic control gear (ECG) is necessary.

For an infinitesimal moment the ECG provides 25.000 Volt, required to ignite the gas contained in the burner. Mortal danger therefore exists. Only for this reason, defective xenon lights should not be replaced by laymen. Something else than the burner might be defective; the ECG or the cable connection could be damaged.

2. Replacing LEDs

Replacing LEDs in the carSeveral types of LEDs are available, like those built on the same sockets as the traditional filament lamps. These LEDs can be DIY replaced in the same way as normal light bulbs. The corresponding DIY light bulb replacement manual applies.

It is different for modern LED lamps and last-generation headlights, where LEDs are integrated in the rear light or the headlight. This means replacing the entire lighting unit. This is a job for a certified garage.

DIY replacement of light bulbs in the car

First should be determined which are the most important lights in the car:

headlights light bulbs– headlights and fog light
front flashing lights light bulbs– front flashing lights
side lights bulbs– side lights (parking lights)
rear lights bulbs– rear lights (possibly with separate reversing light and / or rear fog lamp
light bulbs of the number plate lighting– light bulbs of the number plate lighting
car interior lighting– interior lighting
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In headlights, halogen bulbs have replaced bilux bulbs 10 years ago. 2-thread bilux can be found on 1960ies vintage cars. In addition to the earlier mentioned LED and xenon lamps, halogen lamps are used in headlights. Several types are available, depending on the lighting concept of the car. Therefore, H1 – H3 and H7 lamps have a single filament whereas H4 – H6 are dual-filament bulbs.

Allocation would be as follows:

– H4 – H6 systems with two headlights ( 1 x left, 1 x right)
– H1 – H3 and H7 systems with 4 headlights (2 x left, 2 x right)

Matching halogen bulbs

find matching halogen bulbsIn analogy to 4-headlight systems, there is the option for compact headlights, comprising several lights, fog lamps included. Many Mercedes headlights are an example of this. Furthermore, H7 headlights have a clear panel and H4 a structured glass panel. In case you are uncertain which lamps match the headlights of your car, please consult your car manual.

Another feature of halogen bulbs are the different lamp sockets.

  • H1 to H3 have a short cable piece with a plug, varying according to H-construction. The
  • H5 and H6 sockets differ in size, but are rarely used in cars.
  • H7 and and H4 can be identified by the number of pins sticking out of the socket.

Specifications and important tips for H4 bulbs

tips for H4 bulbsH4 bulbs have 3 pins, arranged at an even distance. These pins differ in size and therefore fit into their fitting in only one position. Just a little force is enough to insert them the wrong way.

Allow us therefore to give you a little mnemonic aid for installation of the still widely used H4 lamps: in the glass tube you see a reflector, which at its front is concave like a small pan. When installing it you should be able to (mentally) spit into this pan. Thus, you are installing H4 the right way around.

We have another important tip regarding light bulb replacement:

Always take them at their socket and never on the glass tube. Our hands and fingers always contain a certain amount of fat, moisture and dirt. The heating of fat and moisture could damage the light bulb. Very often, a finger print on the tube leads to a fogged light panel. Therefore, always touch light bulbs and especially halogen lamps at the metal base because of the high temperature in order to avoid fogged headlights.

DIY replacement of light bulbs of the headlight

Unfortunately, we have some bad news. Light bulb replacement is not necessarily done in a few minutes in every car model. Traditionally, a large screwed-on cover is found at the back of the headlight. This cover must be removed to access to the light bulb and the socket. In several modern cars, the replacement of light bulbs is no longer that easy.

DIY replacement of light bulbs of the headlightSometimes, the entire headlight, the wheel house cover or even the front cowling, and the radiator grille in some models too, must be removed.

Some manufacturers, like Volkswagen have simplified the light bulb replacement in some models after fierce customer criticism. The Golf IV has to go to the garage for a light bulb replacement. In the Golf V the driver can now do it himself.
how to change light bulbs on car headlights

  • Open the bonnet and have a look at the back of the headlight. If its disassembly is obvious, nothing stands in the way of light bulb replacement.
  • For other models it is necessary to obtain information from the car manufacturer if and how the light bulb can be replaced. Many internet forums on specific models can help you here.
  • Some car owners create their very detailed DIY manual.

Light bulb replacement manual for the headlights of your car

Light bulb replacement manual for the headlights of your car

  • Start with buying the fitting lamps, e.g. H7 or H4 light bulbs.
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  • Switch off the ignition, preferably removing the ignition key.
  • Open the bonnet.

how to remove headlights

  • At the back of the headlight you see a grey or black, round cover the size of a hand, which is screwed on.
  • If the cover is tighly fixed, use a towel or gloves in order to apply more force.

how to find a lamp socket on headlights

  • Once the cover is removed, you can see the bottom of the lamp socket. Pull the plug from the socket. Now you see a wire bracket, often on both sides of the lamp socket in the fitting. Following the bracket, you will notice it hangs on the back of the headlight in a rabbet. To remove the bracket, slightly press down at this position and bend both ends together. Now the bracket can be folded down. The light bulb could fall out of the fitting.

how to take out a broken bulb on your car

  • Remove now the broken light bulb, take the new halogen ligh bulb out of its carton at its socket and insert the nose or pins accordingly. In case of H4 light bulbs remember our tip of the reflector pan. Now re-insert the metal bracket, plug in the cable on the bulb and fix the headlight cover.

how to test bulbs on your car

  • Now, test dipped lights and beams.
  • Furthermore, place the car in front of a wall to check the light field of the dipped beam. Particularly, when both lights are at a different level or look in any way irregular, the headlights require adjustment. This can be done in a garage or at several petrol station with the right equipment. This service is regularly offered free of charge.

DIY replacing other light bulbs in the car

1. DIY parking light replacement

DIY parking light replacementThere are several possible positions for parking lights, which can be difficult to reach.

Find the right location with the parking light switched on with help of the still functional parking light on the other side of the car.

2. DIY replacement of side and front turn indicators

DIY replacement of side and front turn indicatorsThis might turn out to be difficult. On some models the turn signal glass cover is screwed on from the outside. Often the signals are intrically fixed with a spring, and you had better consult a garage.

3. DIY replacement of rear light bulbs

Light bulb replacement of the rear lights is mostly done from the inside of the boot.
DIY replacement of rear light bulbs

  • Covers can be found behind the rear lights in the interior panelling. They are either hanging or fixed with screws.

how to remove the car headlight interior trim

  • Remove these to be able to remove the light cover. You now see a kind of circuit board, the lamp carrier which is either screwed to the rear light or just fitted or clamped in. Remove it according to the manufacturer’s repair manual.


  • Now, the separate light bulbs can be replaced. In many models, the plastic light cover must be unscrewed from the outside in order to replace the light bulbs.

how to replace dual-filament light bulbs

  • All these light bulbs can be removed by pressing down gently from the top (tube) into the fitting and then turning sideways and releasing it. These light bulbs have lateral lugs to fit the socket. The number of lugs vary in different sockets and are differently positioned.
  • For dual-filament light bulbs, it is important to install the light bulb the right way around. This is a light bulb for dipped beam (5 W) and brake lights (21 W). If you install the light bulb the wrong way around, both contacts at the lamp socket and therefore rear light and brake light are swapped. Check the correct position of rubber gaskets between light cover and lamp carrier or the rear cover.

4. Replacing light bulbs in the interior and on the number plate light

Replacing light bulbs in the interior and on the number plate light

  • In many models the number plate is illuminated by the rear light. Other cars have a separate number plate light which is simply screwed on as are most lights in the car interior.
  • These bulbs (festoons) look like glass fuses. They are simply and carefully levered out with a screwdriver.
  • Then press in the new festoon until it clicks.

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