Parts for your 2022 Subaru Impreza-Radiator cap

2022 Subaru Impreza radiator cap — purpose, care, and when to replace

Referring to technical sources, the 2022 Subaru Impreza (FB20 engine) does use a conventional, pressurised radiator cap. This is confirmed by the Subaru Owner’s Manual (cooling system section), the Subaru Service Manual/Tech Info cooling system description for FB engines, and the Subaru Genuine Parts Catalogue for MY22 Impreza, which lists a “Cap, Radiator” for the model. It’s located on the radiator’s upper tank under the bonnet, with a separate translucent overflow bottle nearby.

The radiator cap on a 2022 Impreza isn’t just a lid — it’s a pressure regulator that helps the coolant run hotter without boiling, improving heat transfer and preventing cavitation. Inside are two valves: a pressure valve that holds system pressure to a set rating (typically around 1.1 bar) and a vacuum valve that pulls coolant back from the overflow as the engine cools. When the cap is healthy and matched to Subaru’s spec, the engine maintains stable temps, the heater works properly, and coolant stays where it should.

As part of regular servicing, the radiator cap deserves a quick once-over. Only check it when completely cold. Look for perished rubber seals, a sticky or weak spring, corrosion or crust on the seat, and any signs of staining around the neck that hint at weeping. If there’s any doubt, a workshop can pressure-test the cap to Subaru’s spec with a cap tester — it’s a quick job and can save an overheat drama.

Replacement is affordable and straightforward. Stick with an OEM or OEM-quality cap with the correct pressure rating for the Impreza. Avoid “up-rating” the pressure — that can stress hoses, the plastic radiator tanks, and the heater core. When fitting a new cap, make sure the sealing surface on the radiator neck is clean, the overflow hose is snug, and the cap is turned firmly to the second stop. After any cooling-system work, bleed air properly and top up with Subaru-approved long-life coolant premix to the correct level in both the radiator and the overflow bottle.

Common clues the cap needs attention include unexplained coolant loss, slow warm-up, gurgling in the heater, collapsed radiator hoses after cool-down, or temps creeping up on long climbs. Given how critical the cap is, it’s smart to have it inspected at each service and replaced proactively if it shows wear — cheap insurance for the Impreza’s cooling system.

• Check only when cold, never open a hot system.
• Inspect seals, spring action, and the radiator neck seat.
• Test or replace if there’s any sign of leakage, warping, or pressure loss.

Popular questions about 2022 Subaru Impreza radiator caps

Where is the radiator cap on a 2022 Subaru Impreza?
It’s on the top of the radiator under the bonnet — a metal cap marked with a warning. Don’t confuse it with the translucent overflow bottle’s plastic cap, that one isn’t pressurised. Only remove the radiator cap when the engine is completely cold.

How often should the radiator cap be replaced?
There’s no strict kilometre-based interval, but it should be inspected at each service and pressure-tested if there are any cooling concerns. Many owners replace the cap proactively every few years or at the first sign of seal wear, corrosion, or inconsistent pressure.

What pressure cap does the 2022 Impreza use?
Use a cap that matches Subaru’s specified pressure rating for the FB20 engine (commonly around 1.1 bar). The correct rating is printed on the original cap and listed in Subaru service information. Don’t fit a higher-pressure cap — it can overload hoses and plastic tanks.