What does this code mean?
P0442 describes a small leak, P0455 a large leak and P0456 a very small leak. Check the correct fuel-cap seal where fitted, hoses, valves and the manufacturer's leak-test procedure. A loose cap is one possibility, not the only cause. Do not use compressed air or improvised flame tests around fuel vapour.
Sources and interpretation [1]
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0455EVAP System Large LeakManufacturer communications
7Original wording in English
DODGE, JEEP
Reported code forms P0455
Fuel Vapor Hose Not Connected This bulletin involves inspecting and connecting a loose fuel vapor hose. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician…
DODGE, JEEP
Reported code forms P0455
P0455/P0456 Set In The Powertrain Control Module (PCM) This bulletin involves replacing the evaporative emissions purge valve hose due to a split in the hose that will prevent the system from sealing. The customer may…
DODGE, JEEP
Reported code forms P0455
P0455/P0456 Set In The Powertrain Control Module (PCM) This bulletin involves replacing the evaporative emissions purge valve hose due to a split in the hose that will prevent the system from sealing. The customer may…
DODGE, JEEP
Reported code forms P0455
P0455 And/Or P0456 Set In The PCM This bulletin involves replacing the evaporative emissions purge valve hose due to a split in the hose that will prevent the system from sealing. The customer may experience a…
DODGE, JEEP
Reported code forms P0455
P0455 And/Or P0456 Set In The PCM This bulletin involves replacing the evaporative emissions purge valve hose due to a split in the hose that will prevent the system from sealing. The customer may experience a…
DODGE, JEEP
Reported code forms P0455
P0455 And/Or P0456 Set In The PCM This bulletin involves replacing the evaporative emissions purge valve hose due to a split in the hose that will prevent the system from sealing. The customer may experience a…
Check vehicle applicability
5A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Sources and interpretation
These explanations are editorial summaries of the linked manufacturer material. PDF page numbers count from the first file page. Original publications are in English; translations are reference aids. A cited edition is not a claim that it is the manufacturer's latest instruction.
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 11, 12 ·
Source check date · 2026-10-27
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.