Parts for your 2013 Toyota Bb-Fuel cap

2013 Toyota bB fuel cap — purpose, care, and when to replace

Technical references including the Toyota bB Owner’s Manual (QNC20/QNC21 series), the Toyota Electronic Parts Catalogue (EPC) for 2013 model-year bB, and Toyota repair literature for the EVAP (Evaporative Emission Control) system all confirm the 2013 Toyota bB is fitted with a conventional, tethered, screw-on fuel cap. A capless filler isn’t used on this model.

On the 2013 Toyota bB, the fuel cap does more than just cover the filler neck. It seals the tank to contain petrol vapours, supports the EVAP system so emissions stay in check, and helps the engine management maintain proper pressure balance. A dodgy or loose cap can trigger a check engine light with EVAP codes, waste fuel through evaporation, and leave a whiff of petrol around the car. It also keeps dust, water, and road grime out of the tank — a small part with a big job.

The bB’s cap is a click-to-tighten design: twist until it clicks several times. That ratchet action means the seal’s engaged without over-tightening. The rubber sealing ring should be clean, supple, and free of nicks. During regular servicing, it’s smart to give the cap and filler neck a quick look. Wipe away grit with a clean, dry cloth and make sure the tether isn’t cracked or about to let go.

Owners who notice a persistent fuel odour, the cap not clicking, or a check engine light soon after refuelling should start by reseating the cap and driving a few trips — often the light will clear once the system re-tests. If the seal looks flattened, the ratchet’s worn, or the tether’s broken, replacement is inexpensive and worthwhile. Use a genuine or high‑quality cap specified for the QNC2# bB so the pressure relief and venting match factory specs, mismatched caps can keep the warning light on or stress the EVAP system.

• Signs it’s time to replace: fuel smell, cap won’t click, visible cracks or a hard/flattened seal, repeated EVAP codes after refuelling.
• Simple care tips: keep the filler neck lip clean and dry, don’t oil the rubber seal, always tighten until it clicks.

As part of routine servicing in Australia or New Zealand, a quick cap inspection every 10,000–15,000 kilometres (or annually) helps keep the bB tidy, efficient, and compliant.

Popular questions about the 2013 Toyota bB fuel cap

Does the 2013 Toyota bB use a capless fuel filler?

No. The 2013 bB uses a threaded, tethered fuel cap. Toyota’s parts and owner’s manuals for the QNC20/QNC21 series specify a “Cap Sub‑Assy, Fuel Tank,” and the EVAP test procedures assume a sealing cap is present.

Why does my check engine light come on after refuelling?

The most common cause is a loose or worn fuel cap affecting the EVAP system. Refit the cap and tighten until it clicks several times, then drive a few trips. If the light stays on, the cap’s seal may be tired or there may be an EVAP leak elsewhere that needs a technician’s diagnosis.

Should I choose a genuine Toyota cap or an aftermarket one?

Either can work, but it must be specified for the 2013 bB (QNC2#) and meet the correct pressure/venting spec. Genuine parts match the factory calibration and fit, while reputable aftermarket options can be good value. Avoid universal caps that don’t list the bB application.