Parts for your 2017 Subaru Impreza-Drive belt tensioner

2017 Subaru Impreza drive-belt tensioner: what it does and when to service it

Technical sources agree that the 2017 Subaru Impreza (FB20 2.0L) does use a drive-belt tensioner—specifically on the alternator/drive belt—while the A/C compressor runs a separate stretch-fit belt with no tensioner. This layout is shown in the Subaru service manual (Engine: Drive Belt System) and OE parts catalogues for the 2017 Impreza. Reputable aftermarket catalogues for AU/NZ (Gates and Dayco) also list an automatic belt tensioner for the alternator circuit on this model and identify the A/C belt as a stretch-fit type that’s replaced, not adjusted.

On the 2017 Impreza, the drive-belt tensioner’s whole job is to keep the alternator belt at the right tension as conditions change—cold starts, hot runs, electrical load spikes, you name it. By maintaining consistent pressure on the belt, it helps prevent slip and squeal, keeps charging performance steady, and reduces wear on the belt and pulleys. Because the FB20 engine runs electric power steering and a timing-chain-driven water pump, that alternator belt is the main accessory loop, so a healthy tensioner matters if you want reliable battery charging and no annoying chirps under the bonnet.

Servicing-wise, there’s no fixed replacement interval for the tensioner