P0457: the fuel cap is loose, off, or not sealing
The evaporative emission system seals petrol vapour inside the fuel tank and fuel lines instead of letting it escape into the air, and the fuel cap is the part of that seal a driver actually touches. This code means the engine control unit's leak test found a leak that specifically matches the fuel cap not sealing, rather than a leak anywhere else in the system. Unlike a general evaporative system leak code, this one names the fuel cap itself.
You might notice
- No symptom you'd feel while driving, beyond the engine warning light coming on
- A faint smell of petrol near the fuel filler, in some cases
- evaporative emission system
- — seals petrol vapour inside the fuel tank instead of letting it escape into the air
What the code itself says
P0457 is a powertrain (engine, gearbox and drive system) code, and the 0 after the letter means it is a generic code with a standard meaning.
Grouped here as: Fuel vapour system — Catching fuel vapour from the tank and burning it off in the engine. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
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