P0456Powertrain
Evaporative emission system leak detected (very small leak)
Where to start
A very small evaporative leak. The most capricious code of the family: even filling the tank to the brim or a cap not closed until it clicks will produce it. Before hunting for a leak, tighten the cap until it clicks, clear the code and drive for a few days.
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.
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.