P0455 on a Chevrolet

What is different about P0455 on a Chevrolet?

GM's EVAP system uses a more conventional pump-based approach, and the documented failure points beyond the gas cap tend to center on the purge and vent valve solenoids.

What Chevrolet owners run into with P0455

Purge and vent valve solenoid failures: GM truck platforms have a documented pattern of EVAP purge valve and vent valve solenoid failures developing over time, which can cause a large leak code even when the gas cap and hoses are intact.

Gas cap seal wear: As with most makes, a worn or improperly sealed gas cap remains a common baseline cause of P0455 on GM vehicles and should be checked first.

What to check first on a Chevrolet

The order below narrows the generic P0455 list down to what is worth checking first on this make. It is a starting order, not a diagnosis: patterns are generation specific and a vehicle outside those generations may have none of them.

Check in this order

• Check that the gas cap is present, properly tightened, and its seal is intact
• Inspect the EVAP purge valve solenoid and its wiring
• Inspect the EVAP vent valve solenoid, commonly located near the fuel tank on truck platforms
• Inspect EVAP hoses for cracks or disconnection

The generic picture behind P0455

This code sets when the same sealed system pressure or vacuum test used for the small leak code instead finds a leak large enough to fall into the manufacturer's large leak category, typically equivalent to an opening roughly the size of a small tube or an unsealed cap rather than a pinhole. A large leak is usually something obvious once looked for.

Everything on the main P0455 page still applies here. This page narrows the cause list to the patterns documented on Chevrolet vehicles, it does not replace the underlying definition.

The generic version of this code

• P0455 on any vehicle