How to buy car parts online that actually fit

2 min read · Updated 2026-10-26

Use your VIN and OEM numbers, check fitment, avoid counterfeits and know which parts to leave to a professional.

Buying car parts online can save money, but the wrong part costs more than the saving. These steps reduce the risk of ordering something that does not fit.

Start with your car's exact details

Note the make, model, year, engine size, fuel type and trim level. The most precise identifier is the vehicle identification number (VIN), usually printed on the registration document and on the dashboard near the windscreen. Many cars were built with several versions of the same part in the same year, so 'Golf 2015' is often not enough.

Find the OEM part number

The original-equipment (OEM) number is often printed on the old part. You can also get it from a main dealer, an online parts catalogue or the owner's manual. Searching by part number is much more reliable than searching by car model.

OEM versus aftermarket

Aftermarket parts can be good value, but quality varies between manufacturers. Reputable aftermarket brands publish their specifications and the OEM numbers they replace. For critical parts, choose a known brand rather than the cheapest unnamed option.

Treat fitment lists with care

Sellers often include a long compatibility list, and mistakes happen. Before ordering, message the seller with your VIN or OEM number and ask them to confirm the part fits.

Measure what you can

Bulb type (for example H4, H7 or H11), wiper length on each side, connector shape and pin count, thread size on spark plugs and the dimensions of filters are all things you can check against your old part. Pay attention to left and right, front and rear.

Safety-critical parts

Brakes, tires, steering and suspension affect safety. Buy these from trusted brands and have them fitted by a qualified mechanic unless you are experienced. Always replace brake pads in sets for an axle.

Counterfeits

Spark plugs, filters and bearings are commonly counterfeited. Buy from official brand stores where possible, compare packaging with the manufacturer's, and be suspicious when a premium brand costs a fraction of the usual price.

Check the rules where you drive

LED bulbs fitted in housings designed for halogen bulbs can dazzle other drivers and are not allowed on the road in some countries. Check your local rules before fitting lighting upgrades.

Keep your options open

Test-fit the part before installing it fully, keep the packaging and keep your order messages until you are sure it works.

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