Driveable. Check the fuel cap first — missing, cross-threaded or with a perished seal accounts for a large share of these. You may also smell fuel around the vehicle, which is worth mentioning.
A large leak — the system held essentially no pressure or vacuum at all. Because the leak is big, this is the most findable of the evaporative faults, and often the quickest: a missing or badly seated fuel cap, a hose that has come off its stub, or a vent valve stuck open will all produce it.
Start at the filler cap, then follow the pipework by hand looking for a hose that has parted or perished. A leak this size can often be found without a smoke machine, which is not true of P0442 or P0456.
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
P0455 is the EVAP system reporting that it cannot hold pressure at all — a large leak. The system's biggest opening is the one you touch every week: the filler cap. If the code arr...
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