Parts for your 2006 Subaru Forester-Fuel cap

2006 Subaru Forester fuel cap — purpose, care and replacements

The 2006 Subaru Forester absolutely uses a fuel cap. Subaru’s own technical literature confirms it: the Forester owner’s manual instructs drivers to “tighten the fuel filler cap until it clicks,” and the Subaru service manual for the same model year lists EVAP fault code P0457 (fuel cap loose/off) as a diagnostic condition. Those factory references make it clear the cap is a required, functional component of the vehicle’s evaporative emissions system.

On this Forester, the fuel cap seals the filler neck to keep petrol vapours contained, supports the EVAP system so it can self-test properly, and helps prevent dirt and water getting into the tank. It’s got a ratcheting design so it tightens to the correct tension, then clicks to protect the seal and thread. A healthy cap helps avoid fuel smells, keeps the check engine light at bay, and protects the environment by reducing vapour loss.

Because the cap’s rubber seal hardens and cracks with age, it’s worth treating it like a small but important service item—especially on an SG-chassis Forester that’s now well over a decade old. Quick care pointers:

• Wipe dust from the filler neck and cap seal at each service.
• Inspect the O-ring for nicks, flattening or hardening, replace if in doubt.
• Ensure it “clicks” three times when tightening, if it won’t click or spins freely, replace it.
• Avoid petroleum-based lubes on the seal, if needed, a tiny wipe of silicone-safe rubber conditioner is fine.

Replacement is straightforward:

• With the engine off, turn the old cap anti-clockwise and remove.
• Check the filler neck for debris and clean lightly.
• Install the new cap and tighten clockwise until it clicks several times.

For fitment, use a cap that meets Subaru EVAP specs. Genuine Subaru caps commonly used on 2006 Forester models include part numbers in the 42031FE000 family, depending on market. A proper cap helps prevent EVAP-related fault codes like P0442, P0455 and P0457. If a loose or faulty cap has triggered a warning, the light often clears itself after several drive cycles once a good cap is fitted and tightened correctly.

As a rule of thumb, if the cap’s seal looks tired, the tether is broken, or the cap doesn’t click reliably, it’s time to swap it—cheap insurance for smooth motoring across Aussie and Kiwi roads.

Popular question: What are the signs the 2006 Forester’s fuel cap is failing?

Common clues include a fuel smell near the left-rear quarter after refuelling, the check engine light with EVAP codes (often P0457 for cap loose/off), and the cap not clicking when tightened. A cracked or flattened O-ring, or a cap that feels wobbly on the neck, also points to replacement time.

Because EVAP faults can come from other hoses or valves, start with the cap—it’s quick to check and often the most economical fix.

Popular question: Which fuel cap fits a 2006 Subaru Forester?

Use a cap designed for the SG Forester’s EVAP system. Genuine Subaru caps in the 42031FE000 range are commonly specified for this era. Quality aftermarket caps that state Subaru Forester 2003–2008 compatibility and meet EVAP standards are fine, but avoid generic “one-size” caps that don’t click or seal correctly.

Popular question: Is it okay to drive without the fuel cap for a short trip?

Not recommended. The Forester relies on the cap to seal the tank, running without it can trigger a warning light, vent petrol vapour, and let dust or water into the filler neck. If the cap’s lost, fit a correct replacement promptly to protect the EVAP system and avoid contamination.