Original or aftermarket

Most parts on this site are offered in one of two tiers. You will see them labelled Original / Genuine and Aftermarket. They are matched to your vehicle the same way, on the same OE number, and they carry the same warranty and the same return rights. What differs is who made the part and what you are paying for.

This page explains the difference honestly, including where the more expensive option is worth it and where it is not, so you can decide for the job in front of you rather than being told what to buy.

What Original / Genuine means

An Original or Genuine part is the part as the vehicle manufacturer supplies it, to the vehicle manufacturer's own specification, carrying the vehicle manufacturer's part number.

In practice this means:

• It is the same specification as the component the vehicle left the production line with, or the revision the manufacturer replaced it with.
• Dimensions, materials, coatings, connectors, mounting geometry and any electronic behaviour are what the vehicle was designed and validated around.
• Where a part needs to talk to the rest of the vehicle, it has been built to do so as the vehicle expects.

Worth knowing: the vehicle manufacturer rarely makes every part itself. Many components are designed and produced by independent manufacturers under contract, then supplied to the vehicle maker and sold under the vehicle maker's number. That is normal and it has been the way the industry works for decades.

What Aftermarket means

An Aftermarket part is made by an independent manufacturer to serve the same application, and sold under that manufacturer's own number with the vehicle manufacturer's OE number listed as a cross-reference.

In practice this means:

• The part is designed to fit and function in place of the original.
• The manufacturer is free to choose its own materials, tolerances and production methods within the constraints of the application and the law.
• Quality varies by manufacturer far more than it varies by tier. A serious aftermarket manufacturer with its own engineering and testing is a different proposition from an anonymous copy, even though both sit in the same tier.

That variation is the honest heart of the matter. Aftermarket is a description of origin, not a grade.

Where the difference actually shows up

Not everywhere. On a simple mechanical item that has to be the right shape and the right material, the two tiers frequently behave identically for the life of the part. The differences tend to appear in these places:

• Tolerance and fit. How tightly the part matches the space it goes into, how the panel gaps line up, whether a bracket needs persuading.
• Materials and coatings. Corrosion protection, the grade of a rubber compound, the friction material in a braking component, the plating on a fastener.
• Electronic behaviour. Whether a sensor reads the same way, whether a module answers the vehicle correctly, whether the part needs coding or calibration after fitting.
• Longevity. Two parts that both work on day one can diverge sharply after a winter.
• Cosmetic finish. Texture, grain, gloss level and colour match on anything visible.

Where Original earns its money

Choose Original where the cost of the part being slightly wrong is much larger than the price difference:

• Safety-critical systems, covered separately below.
• Anything that has to be coded, calibrated or learned by the vehicle, including control modules, some sensors, and components tied to driver assistance systems. If a part has to be introduced to the vehicle electronically after fitting, an exact match saves an expensive afternoon.
• Anything visible on the outside of the car, where paint match, grain and panel gaps are judged at arm's length.
• Sealing and structural interfaces, where a small dimensional difference becomes a water leak, a wind noise or a stress point.
• A vehicle still inside its manufacturer warranty, where you want no argument about what was fitted.
• A part you do not want to do twice, because the labour to reach it is expensive or the vehicle is off the road while it is out.

Where Aftermarket makes good sense

Choose Aftermarket where the application is well understood and the risk is contained:

• Routine service and wear items on an older vehicle, where the part is a commodity and the specification is not exotic.
• Parts hidden from view, where finish and grain do not matter.
• Simple mechanical components with no electronics and no calibration.
• A vehicle you are keeping for a defined and shorter period, where matching the original specification exactly buys you nothing you will use.
• Cases where the aftermarket manufacturer is a known engineering business, sometimes the same business that supplied the vehicle manufacturer in the first place.
• Cosmetic or interior items where a good part at a lower price is simply a better use of money.

None of that is a compromise dressed up. A well-made aftermarket part fitted correctly to the right application is a sound repair, and the trade has been doing it for as long as there have been cars.

Safety-critical parts: the straight version

Some parts, if they fail, do not merely stop working. They change whether the vehicle stops, steers, holds together or protects the people inside it. That group includes braking components, steering components, suspension and load-bearing chassis parts, restraint systems and airbag-related components, towing equipment, wheels and their fixings, lighting, and glass.

Here is the honest position.

The tier is not the whole answer. A safety-critical part is acceptable when the manufacturer behind it can be identified, has engineering and testing behind the product, and holds the approvals the part legally requires. Some aftermarket manufacturers clear that bar comfortably. Some products in the market do not.

Look for the approval markings. Lighting and glass carry type approval marks. Braking friction material carries an approval reference. Where a part legally requires an approval, the marking is on the part, and its absence is a warning worth acting on.

Price that looks impossible usually is. A safety-critical part offered far below every other source is telling you something about what was left out.

Restraint systems are a special case. Airbags, belt tensioners and their control components should be treated as replace-with-Original unless a workshop with the right equipment tells you otherwise. They deploy once, they cannot be tested in place, and the failure mode is not a breakdown.

Have safety-critical work done by a qualified workshop. Beyond the obvious reason, our voluntary guarantee requires professional installation and proof of it, and torque figures and procedures on these parts are not optional.

If you are unsure which tier to take on a safety-critical job, ask us and tell us what the vehicle is used for. We will give you a straight answer rather than the expensive one. More on our safety obligations and the information published with every offer is on the product safety page.

How to decide, in five questions

1. What happens if this part fails? Inconvenience, or something worse? The worse the failure, the stronger the case for Original.
2. How hard is it to fit? If the labour to get to it dwarfs the price of the part, buy the one you will not be replacing again soon.
3. Does the vehicle have to accept it electronically? If yes, an exact match removes a category of problem.
4. Will anyone see it? If yes, finish and colour match matter and Original is the safe answer.
5. How long are you keeping the vehicle? A long horizon justifies specification. A short one justifies sense.

If four of those answers point the same way, you have your decision. If they are split, take Original on the safety-critical part and Aftermarket on the rest of the job.

What is the same either way

Whichever tier you choose from us:

• The part is matched on the same OE number, so fitment is judged the same way. See Finding your OE number and Fitment and compatibility.
• You get 24-month warranty, 30-day returns. The statutory two-year conformity right applies in full and is never conditioned on anything. Our voluntary guarantee sits on top of it, with its conditions set out on the warranty page.
• Return rights are identical. Read the returns page before you order if you want to know exactly who pays for what.
• The checkout shows the delivery cost and any import charges that apply to your destination before you confirm the order.

What we do not claim

We do not describe an aftermarket part as though it were the original, and we do not describe an original part as though it were the only defensible choice. Where a part is Aftermarket, the listing says Aftermarket. Where we do not know something about a part, we say so rather than filling the space.

If a listing is unclear about which tier you are looking at, tell us through the contact page and we will fix the listing, not the answer.

Still not sure?

Send us the OE number and tell us what the job is. Use the OE number search if you have the number, the vehicle finder if you do not, or the quote form if you would rather a person looked at it. We answer within 24 hours, usually within a few hours.