P0455Powertrain
Evaporative emission system leak detected (gross leak)
Where to start
A large evaporative leak. The fuel cap is open, missing or no longer sealing at all. If the cap is fine, look for a chafed hose or a cracked charcoal canister.
A code is not a diagnosis. It says which check failed, not which part to replace. Clearing it without repair only means the car will report it again in a few trips.
How to put together a report a mechanic will actually read
We have a detailed piece on thisThe fuel cap: codes P0455, P0442 and P0457
How the code is built
Letter — the systemPowertrain: engine and transmission
Common or the maker's ownGeneric code: the same on every car
Which part of the engineEmission controls: catalyst, EGR, fuel vapour
Number of the faultThe serial number inside that group — it does not say how serious the fault is
All codes in «Fuel vapour leaks»
How it feels behind the wheel
The same fault shows itself in different ways. Each sign below says what to look at in the live data.
Hard to start when hotIt starts instantly from cold, but after a drive it cranks for a long time and catches reluctantly. Pressing the throttle sometimes helps.It smells of petrolA fuel smell in the cabin or around the parked car. Sometimes with the Check Engine lamp on.Check engine came on after refuellingYou filled up, drove a few kilometres, and the light came on. The car drives exactly as before.
How the app helps
CarScan reads this code from your car through an OBD-II adapter, shows whether it is active now or only stored, names the module that reported it, and puts it into a plain-text report for your mechanic.