Parts for your 2010 Subaru Impreza-Fuel cap

2010 Subaru Impreza fuel cap: what it does and when to replace it

Referencing Subaru’s 2010 Impreza Owner’s Manual, the Subaru Genuine Parts Catalogue (listing an OEM screw-type cap, e.g., 42031FG030, for 2008–2011 Impreza), and standard EVAP/ORVR system notes in Subaru service literature, the 2010 Subaru Impreza is fitted with a conventional, tethered, screw-on fuel cap. It is not a capless design. Those sources also note EVAP leak diagnostics (including DTCs such as P0457) that can be triggered by a loose or damaged cap, so the fuel cap is very much relevant on this model.

On a 2010 Subaru Impreza, the fuel cap seals the petrol tank and the evaporative emissions (EVAP) system. That sealed fit keeps petrol vapours from escaping to the atmosphere, maintains correct tank pressure for EVAP self-tests, and helps the car run clean while meeting emissions rules. Day to day, it’s the humble bit that stops fumes and keeps dust, water, and road grime from sneaking into the filler neck. Subaru specifies tightening the cap until it clicks, which confirms the seal is snug.

As part of regular servicing, it’s worth giving the cap a quick once-over. Check the tether isn’t torn and the rubber gasket (O-ring) isn’t cracked, flattened, or sticky. Wipe the sealing surface with a clean, dry cloth—no lubricants or silicone sprays, as they can swell seals or attract grit. If the car throws a Check Engine Light after refuelling, first ensure the cap is properly tightened (three clicks). If the light persists after a few drive cycles, the cap or EVAP system may need attention.

When replacement time rolls around, stick with an OEM-quality cap designed for the Impreza’s EVAP calibration. A mismatched cap can cause weak sealing, fuel odour, or repeated EVAP fault codes. Swapping the cap is as simple as unscrewing the old one and clicking the new one on, keep the tether tidy so it doesn’t get pinched. Many owners replace the cap proactively every few years—especially in hot, coastal, or dusty conditions common around Australia and New Zealand—to avoid nuisance warnings.

Signs a new cap is due can include:

• Fuel smell around the rear quarter or in the cabin after parking
• Visible cracks or a hardened gasket
• Frequent EVAP-related fault codes or a cap that won’t click tight

Quick service tip list:

1. Tighten after every fill until it clicks.
2. Inspect the gasket at each oil change.
3. Clean the sealing face, avoid lubricants and harsh solvents.
4. Use a cap specified for 2010 Impreza if replacing.

FAQ: 2010 Subaru Impreza fuel cap

What fuel cap fits a 2010 Subaru Impreza?
It uses a conventional, tethered screw-on cap matched to the Impreza’s EVAP system. An OEM reference often cited in Subaru parts catalogues for 2008–2011 Impreza is 42031FG030. Aftermarket is fine if it specifically lists 2010 Impreza compatibility and meets EVAP requirements.

Will a loose fuel cap cause a Check Engine Light?
Yes. A loose, damaged, or incorrect cap can set EVAP leak codes (commonly including P0457). Refit until it clicks and drive a few trips, if the light stays on, inspect the gasket or replace the cap before chasing other EVAP faults.

How often should the cap be replaced?
There’s no strict interval, but inspecting at each service is smart. In harsher climates or high‑kilometre use, many owners replace the cap every 3–5 years or at the first sign of sealing wear, odour, or recurring EVAP warnings.