Parts for your 2021 Subaru Impreza-Head gasket

2021 Subaru Impreza head gasket: what it does and when to sort it

Yes, the 2021 Subaru Impreza does use head gaskets. Technical references including the Subaru Factory Service Manual for MY2021 Impreza (FB20 engine), Subaru’s service information platform used by dealers, and the official Subaru parts catalogue all list multi-layer steel (MLS) cylinder head gaskets for the FB-series 2.0‑litre flat-four. Because it’s a boxer layout with two cylinder heads, this Impreza runs two head gaskets—one per bank.

The head gasket’s job is to seal the combustion chambers and the oil and coolant passages between the aluminium block and the alloy cylinder heads. In the 2021 Impreza’s FB20, the MLS gasket design helps handle thermal cycling, keeps compression tight, and stops oil and coolant from mixing. It’s a quiet achiever that keeps the engine running sweet under the bonnet, day in and day out.

While older EJ-series Subarus built a reputation for head gasket dramas, the FB-series in the 2021 model is far less prone thanks to improved gasket materials, revised cooling flow and better surface finishes. Even so, like any modern engine, abuse, overheating, poor coolant quality or neglected servicing can shorten gasket life.

• Signs it may be on the way out: unexplained coolant loss, sweet-smelling white exhaust, milky residue under the oil cap, misfires on cold start, pressurised hoses when cold, or rising temps on long climbs.

As part of routine servicing, a workshop should check coolant condition and level, pressure-test the system if there’s any doubt, and look for staining around hose joints and the head-to-block seam. Sticking with the correct Subaru-spec long-life coolant mix and replacing it at the intervals in the owner’s manual goes a long way to keeping the gasket happy. Avoiding overheating—think clean radiators, healthy fans, and proper bleeding after coolant changes—matters just as much.

Head gaskets aren’t a scheduled replacement item