How to check a car part fits your exact car
Most wrong-part returns don't happen because the buyer was careless. They happen because two cars that look identical from the outside take different parts underneath. A Golf Mk5 and a Mk6 share a shape and a badge but not a wishbone. A pre-facelift Polo takes a different headlight to the facelift built a year later.
Here's how to be certain a part fits before you spend anything.
1. Start with your registration
Your number plate is the fastest route to a match. On eBay and most parts sites you can enter your reg and the listing will tell you whether the seller has confirmed it fits. It's not infallible — it depends on the seller keeping their compatibility data accurate — but it filters out the obvious mismatches in seconds.
Treat a reg match as a strong hint, not a guarantee. For anything mechanical, confirm with the checks below.
2. Know your engine code
For anything attached to the engine — timing belt, water pump, turbo, glow plugs, coil packs — the model and year aren't enough. The same car can be sold with several engines, and parts differ between them. A 1.6 TDI and a 2.0 TDI take different belts even in the same bodyshell.
Your engine code is a short string of letters and numbers (for example CAYC or CJAA). You'll find it on the V5C logbook, on a sticker in the engine bay or cambelt cover, and often stamped on the block itself. Match the code, not just the litres.
3. Check your trim and options
Sportier trims often run bigger or different hardware. GTI, R, GTD and similar versions frequently use larger brake discs and calipers, uprated intercoolers and specific dampers. Stop/start cars use different starters and alternators. Cars with or without air conditioning can use different radiators.
If the listing lists a trim or an option and yours doesn't match, ask the seller before buying.
4. Watch for the facelift
Manufacturers quietly update models partway through a generation — the 'facelift'. Lights, bumpers, grilles and interior trim are the parts most likely to change at that point. If your car sits near the changeover year, check whether you need the pre-facelift or facelift version.
5. Match the old part
The surest check of all: compare against the unit you're removing. Note the part number stamped on it, count electrical connector pins, check left/right and front/rear, and measure where you can. A five-minute comparison beats a wrong-part return every time.