How to Replace Wiper Blades
Another quick winter-visibility job you can do yourself: the right blade sizes, removal without cracking the glass, and a proper test.
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A headlight that's out is easy to miss from the driver's seat and easy to spot from every other car, especially now the evenings are dark. On many cars, changing the bulb takes ten minutes and no tools. On some it means reaching through a tight gap, and on cars with xenon or LED headlights it often isn't a bulb you can change at all. Most failed attempts go wrong before the bonnet is even open: the wrong bulb was bought, or the owner didn't know which kind of headlight their car has. So this guide starts there. You'll find your exact bulb code and check whether it's a DIY job on your car, then swap the bulb without touching the glass, and test and check the result.
What you'll be able to do: Identify the correct headlight bulb for your car, decide whether it's a job you can do yourself, replace it safely, and check both beams work and point the right way.
Outcome: "I have my car's exact headlight bulb code written down, and I know whether my headlights take a bulb I can replace myself."
Open your owner's manual at the bulb or lamp section (often near the back, under specifications) and find the headlight entry. Write down the code you see there, for example H7, H11 or 9005.
Headlight bulbs are identified by a code, such as H4, H7, H11, 9005 (also called HB3) or 9006 (HB4). Low beam and high beam often use different codes, and so can fog lights. You'll find the codes in the owner's manual, in a parts store's lookup by make, model and year, or printed on the base of the old bulb. Get the code before you buy. Two bulbs that look almost the same won't fit each other's sockets. Next, check which kind of headlight your car has. Most cars use halogen bulbs, which are cheap and designed to be replaced by the owner. Xenon (HID) headlights run at very high voltage, and the manual usually tells you to leave them to a garage. Many newer cars have LED headlights built in as a sealed unit, so there's no separate bulb to change. The manual or the parts lookup will say which you have. Finally, look at how you reach the back of the headlight. On many cars you can reach it from the engine bay. On some you need to turn the steering wheel and open a flap in the wheel-arch liner, and a few need the battery, air box or even the bumper moved. If the manual's instructions involve the bumper, a garage is a reasonable choice.
A driver's left low beam is out. They nearly buy a twin pack labelled H7 because it looks like the bulb in a friend's car. The parts store's lookup for their make, model and year shows H11 for low beam and 9005 for high beam. The manual agrees, and also shows that the low-beam bulb is reached by turning the wheel and opening a small flap in the wheel-arch liner. They buy an H11 pair and know in advance where to reach.
Outcome: "I can remove the old headlight bulb and fit the new one without touching the glass or breaking the connector."
Take the new bulb out of its packaging by holding only the plastic or metal base, and look at the tabs on it. Match them to the shape you'll find in the headlight.
Switch off the engine and the lights, and remove the key. If the light has been on, let the old bulb cool for a few minutes, as halogen bulbs get very hot. Reach the back of the headlight (Chapter 1) and remove the rubber or plastic dust cover if there is one. Unplug the electrical connector from the bulb: press its release tab and pull it straight back, by the plastic, not the wires. Then release the bulb. Most twist out a quarter turn anticlockwise. Others are held by a wire spring clip that you press in and swing aside. Lift the old bulb straight out. Hold the new bulb only by its base. Don't touch the glass. Oil from your fingers creates a hot spot on a halogen bulb that can shorten its life or crack it. If you do touch it, clean the glass with a little rubbing alcohol on a clean cloth before fitting. Line the tabs up with the slots, push the bulb in and twist it, or refit the spring clip, until it sits firmly without wobbling. Reconnect the plug until it clicks, refit the dust cover so moisture can't get in, and close any flap you opened.
Working through the wheel-arch flap, someone can't get the connector off the old bulb by pulling, and pulls harder on the wires. They stop, use a torch, and see a small release tab on top of the plug. Pressing the tab with a thumb, the plug slides off easily. The old bulb twists out a quarter turn. They fit the new one holding it by the base, twist it until it locks, and push the plug back on until it clicks.
Outcome: "I can test both beams after the change, know why bulbs are best replaced in pairs, and check that the beam points where it should."
Park facing a wall or garage door after dark, switch on the low beams, and look at the two light patches side by side.
Before you put the tools away, switch on the low beams, then the high beams, and walk round the front of the car to check both sides. If the new bulb doesn't light, check that the connector is fully clicked on and the bulb is seated, before suspecting the bulb or a fuse. Bulbs are usually sold in pairs, and there's a good reason to change both together. Halogen bulbs dim with age, so an old bulb next to a new one gives uneven light. And the other bulb, of the same age, is often not far behind. Parked facing a wall or garage door at night, the two low-beam patches should be at the same height, with the top edge of each a little below the height of the headlights themselves. If one side is clearly higher or lower than the other, the bulb may not be seated properly, so check that first. If it still looks wrong, or you've changed a whole headlight unit, have the aim checked at a garage or a test centre, because a beam that's too high dazzles oncoming drivers. Driving with a headlight out can get you stopped in many places, so it's worth carrying the spare bulb from the pair if your car takes a bulb you can reach easily.
After replacing only the failed left bulb, a driver notices at a wall that the left patch is whiter and brighter than the right. A week later the right bulb fails on a wet evening. Next time, they change both sides at once, and keep a spare low-beam bulb in its box in the glovebox. On the wall test, both patches now match in colour and height.
The complete guide — all 3 chapters, every checklist and exercise — as a clean, printable PDF. No email required.
Every guide on this site is produced with the Self-Directed Learning Framework: instead of an article that explains a topic at you, the framework turns it into a structure you work through — each chapter with one outcome, a starting action under twelve minutes, the minimum you actually need to know, a worked example, a checklist, and exercises. It starts from three questions:
Topic: Changing a car headlight bulb.
Outcome wanted: Replace a failed headlight bulb with the right part, and know when it's a garage job instead — within three days.
Starting point: Drives daily, has noticed a headlight out, has never opened the back of a headlight and isn't sure which bulb to buy.
The prompt framework behind it is public: see the C.R.A.F.T. prompt framework, including the exact prompt that generated this library.
Another quick winter-visibility job you can do yourself: the right blade sizes, removal without cracking the glass, and a proper test.
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