PROBLEMS & DIAGNOSTICS
2015 Chevrolet Silverado 1500 P0442 & P0455 EVAP Leak Codes
P0442 describes a small evaporative-emissions leak; P0455 describes a larger detected leak. A loose fuel cap is one possibility, not a guaranteed fix.
Confirm the engine, trim, drivetrain, market and installed equipment before using a part number, capacity or repair procedure.
EVAP code differences
| Code | General meaning | Starting check |
|---|---|---|
| P0442 | Small EVAP-system leak detected | Cap seal and small hoses |
| P0455 | Large EVAP-system leak detected | Cap, disconnected hose, vent/purge operation |
The engine controller performs its test under specific operating conditions.
What the EVAP system does
The sealed fuel-vapour system stores fuel vapours and sends them to the engine under controlled conditions. A loose or damaged cap, leaking hose, filler-neck seal, vent valve, purge valve or charcoal canister connection can affect pressure testing. Inspect for a raw-fuel smell or visible leak before routine driving.
What to check in order
Start with the actual fuel-cap and filler seal condition, then record whether the code appeared shortly after refuelling. Inspect obvious hoses and connector damage. A shop can command purge and vent valves with a scan tool and perform an EVAP smoke/pressure test using fuel-safe equipment. Do not use an open flame or household smoke source.
- Tighten or replace a damaged cap only if it actually fails inspection.
- A code may need several drive cycles to clear after a genuine repair.
- If fuel is leaking or vapours are strong, stop and seek professional service.
Use the correct model-year manual and current service information. Stop if instructions or safety precautions are unclear, and use a qualified technician for work you cannot verify.
References and further reading
This independent guide is not endorsed by the vehicle manufacturer. Let us know if you spot an error.