A tensioner’s job is pretty straightforward. It maintains the correct amount of tension on your serpentine belt – that big rubber belt that runs all your engine accessories like your alternator, power steering pump, and AC compressor. It's basically a spring – loaded arm that pushes against the belt, keeping it tight. Some tensioners are automatic, meaning they adjust continuously, while others require manual adjustment. Think of it this way: that belt is powering a lot of important stuff. If it slips, those things don't work. The tensioner stops that slippage. It makes sure the belt wraps around all the pulleys properly and spins them at the right speed. It's a small part, but it’s part of a critical system. A failing tensioner can cause all sorts of headaches. You'll likely notice a whining or squealing sound, especially when you first start the car or when you put a load on the accessories – like turning on the AC. If it gets really bad, the belt can slip completely, and then you could lose power steering, your battery won't charge, and your AC will stop working. It really acts like a shield against those problems. Ignoring it will lead to more expensive repairs down the road. A worn tensioner can also damage the belt itself and even the pulleys. You’ll notice if the belt starts to fray or show signs of wear prematurely. We carry a good selection of tensioners at Fixparts Online, and getting a new one is a relatively inexpensive fix that can save you a lot of trouble. Confidence in every purchase: Tensioner (MPN 12311717898) is covered by a 12-month warranty!

About BMW

Mercedes-Benz is a luxury automotive brand known for its advanced technology, elegant design, and superior performance.

Why Choose BMW?

• Get parts made specifically for your BMW, so they fit and work perfectly. • BMW parts are known for their high quality and durability, meaning they last longer. • Using genuine BMW parts helps maintain your vehicle’s value. • You can trust BMW parts to keep your car running smoothly and safely. Performance you can rely on – BMW parts from FixParts Online.