P0455 — Large leak detected in the fuel vapor system
A large leak was found in your car’s evaporative emission system, which controls fuel vapors to reduce pollution. This code appears when the system can’t hold pressure, often due to a loose or missing gas cap or a damaged hose. It doesn’t usually affect driving safety but can cause fuel smell and increase emissions.
Common causes
The cause is almost always one of a few things. Here they are — P0455 rarely comes from anything outside this list:
- Loose or missing gas cap
- Cracked or disconnected EVAP hose
- Faulty or damaged charcoal canister
- Leaking or broken purge valve
- Damaged fuel tank or filler neck
Where to start
In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:
- Check and tighten or replace the gas cap
- Inspect and reconnect or replace EVAP hoses
- Test and replace purge valve if faulty
- Inspect charcoal canister for damage and replace if needed
- Check fuel tank and filler neck for leaks
That is what holds for P0455 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.
Why TorqFix for your car?
Above is what the code means and why it appears. TorqFix goes further — it gives you specific procedures, torque values, wiring diagrams and pinouts for your exact engine, not generic steps for every car. Real workshop data (127,000+ diagrams, 10,000+ procedures), interpreted by AI in your language.
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Code breakdown
🔧 Related repair procedures
- VW: Removing and installing starter catalytic converter
- VW: Checking Lambda probe and Lambda control before catalytic converter
- AUDI: Removing and installing front exhaust pipe with catalytic converter
- AUDI: Removing and installing front exhaust pipe with starter catalytic converter
- AUDI: Removing and installing front exhaust pipe (right-side) with catalytic converter - vehicles with manual gearbox
- AUDI: Checking lambda probe and lambda control downstream of catalytic converter
- AUDI: Removing and installing front exhaust pipe (right-side) with starter catalytic converter and main catalytic converter - vehicles with manual gearbox or multitronic gearbox 01J
- AUDI: Removing and installing catalytic converter
- AUDI: Removing and installing front exhaust pipe (left-side) with catalytic converter - vehicles with multitronic gearbox
- AUDI: Removing and installing catalytic converter - vehicles with two turbochargers
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
The same code can mean different things on different makes. Match the meaning to your make before acting on it.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
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