How to Add a Lock to a Non-Locking RV Fuel Door

It is one of the most common questions on the RV forums: “My fuel door doesn’t lock — how do I add a lock?” Whether you are on a motorhome chassis with an exposed fill or a trailer with a flimsy friction door, the factory almost never gives you real security at the fuel fill.

The options owners usually try (and their downsides)

• A locking gas cap. Cheap and easy — but most use the universal CH751 key, and many aftermarket caps trip a check-engine light by breaking the EVAP seal. On diesels you also lose the OEM cap’s tether and seal.
• A padlock or hasp. Ugly, rattles, and rarely fits the fuel-door area cleanly.
• Doing nothing. The most common choice — and the reason tampering and casual siphoning happen in the first place.

The clean retrofit: a dedicated locking fuel door

The RV Fuel Vault is built specifically to add a lock where there wasn’t one. It is a locking fuel door, not a replacement cap, and here is why that matters:

• It locks over your factory cap. Your OEM cap and EVAP seal stay in place, so there is no check-engine light.
• Keyed different from the universal CH751 — a stranger’s universal key won’t open it.
• Anti-tamper security screws included so the door can’t just be unscrewed.
• Installs in about 8–15 minutes with basic hand tools; built from 3/16" High Impact Reinforced Material.
• Keyed-alike multi-packs so one key opens every door you add.

How to do it, step by step

1. Confirm your fit. Use Find My Fit to match the correct door to your motorhome, 5th Wheeler, or travel trailer.
2. Remove or open the existing fuel-door area per the instructions included with your door.
3. Mount the RV Fuel Vault over the fill using the included anti-tamper screws — your factory cap stays right where it is.
4. Lock it and keep your keyed-different key. That’s it.

“A thief will just drill it”

Sure — a determined thief can defeat almost anything. But the real, everyday threat to RVers is opportunistic: an open or non-locking fill and a quiet moment. Adding a real lock removes that easy opportunity, which is what actually protects your rig.

Ready to add a lock the right way? Start with Find My Fit or call +1-941-732-0452.