OEM or aftermarket parts: what is the difference?

2 minute read · Checked October 2026 · Written at the Harkness counter, Coppervale, BC

The short answer

OEM parts come from the carmaker, in its box, built to its spec. Aftermarket parts come from other companies, and quality runs from excellent to bargain grade. For brakes, suspension and exhaust, a good aftermarket part is often the smart buy. For sensors and electronics, OEM often saves a second visit. We tell you which, and why.

What does OEM mean on a car part?

OEM stands for original equipment manufacturer. An OEM part is the one your car was built with, sold through the carmaker's parts network. It matches the factory part number, so it fits and works the way the engineers planned.

Carmakers buy many parts from supplier companies. The same supplier often sells a near match under its own brand. These are sometimes called OE or OES parts. They usually cost less than the boxed OEM part.

How do OEM vs aftermarket parts compare on price and quality?

OEM parts usually cost more. Aftermarket parts cover a wide range. The best brands match or improve on the factory part, and some fix a known weak spot. The cheapest ones can fit poorly or wear out fast. The brand and the grade matter more than the label.

Labour does not change with the part. A brake job books the same time with either one, at $118 an hour. Our warranty is 12 months or 20,000 km either way. See our services and from-prices for each job.

When does OEM make more sense?

Sensors and electronics are the clearest case. Engine computers expect a sensor to read a certain way. Some aftermarket sensors read a little differently, and the check engine light can come back. Keys, modules and some trim parts also tend to fit best from the factory.

Fluids follow the same idea. Coolant, transmission fluid and oil each have a spec in your owner's manual. We use the one your engine calls for. If the light is already on, start with a diagnostic hour so the right part gets ordered the first time.

When is aftermarket the better buy?

Wear parts are where good aftermarket shines. Brake pads come in compounds for different jobs. A pad built for towing on long grades can suit a Kootenay truck better than the stock one. Some aftermarket suspension parts add grease fittings, which help on gravel and Forest Service Roads.

Exhaust pipe is another good case. Road salt eats it, and a well-made aftermarket section welds in at a fair price. On older vehicles, the factory part may no longer be made at all. Then a quality aftermarket or rebuilt part is the way to keep the car on the road.

Asked at the counter

Will aftermarket parts affect my new car warranty?

That depends on your warranty terms and on what caused a failure. We walk through it in our guide to servicing outside the dealer in Canada. Either way, keep every invoice that shows the part and fluid specs used on your car.

What is a remanufactured part?

A remanufactured part is a used unit rebuilt to spec with new wear parts. Alternators, starters and brake calipers are often sold this way. They usually cost less than new, and many carry their own warranty. We tell you when one makes sense for your car.

Can I choose which kind of part goes on my car?

Yes. When a job has a real choice, the quote shows the options with their prices. We tell you which one we would put on our own car and why. You pick, and the invoice names the brand and part number we fitted.