P0442: there's a small leak in the fuel vapour system
The evaporative emission system seals petrol vapour inside the fuel tank and fuel lines instead of letting it escape into the air, and the engine control unit checks that seal by pressurising or drawing a vacuum on it and watching how well it holds. This code means the system lost pressure faster than it should for a small leak, somewhere between the fuel cap and the parts the computer can test.
You might notice
- No symptom you'd feel while driving, beyond the engine warning light coming on
- A faint smell of petrol, 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
P0442 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.
Stop reading. Start diagnosing.
Two minutes, free, and it'll be about your car rather than every car.