Reference meaning
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.
Narrow by vehicle
A 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.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0442EVAP SMALL LEAK
P0442EVAP SMALL LEAK
P0442EVAPORATIVE EMISSION (EVAP) SYSTEM LEAK
Manufacturer communications
278Original wording in English
AUDI
This bulletin provides information when the fuel tank cap seal is leaking; DTC P044200, P045600 and/ or P00EF00 in stored in the ECM.
VOLKSWAGEN
Oil leak from Cylinder Head Cover; Customer states transmission error on dash/unable to move shifter out of park; Customer states MIL-on, P0456, P0442, or P04F0 stored in ECM memory; Customer states MIL-on; Customer states dynamic road sign assist error messages on instrument cluster and center display; Customer states wind nois…
VOLKSWAGEN
Oil leak from Cylinder Head Cover; Customer states transmission error on dash/unable to move shifter out of park; Customer states MIL-on, P0456, P0442, or P04F0 stored in ECM memory; Customer states MIL-on, fault P2080 present; Customer states MIL-on; Customer states dynamic road sign assist error messages on instrument cluster …
VOLKSWAGEN
Oil leak from Cylinder Head Cover; Customer states MIL-on, P0456, P0442, or P04F0 stored in ECM memory; Customer states MIL-on, fault P2080 present; Customer states MIL-on; Customer states various error messages on the cluster; Customer states dynamic road sign assist error messages on instrument cluster and center display; Cust…
Check vehicle applicability
3901A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
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 · 2024-04-16
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.