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.
P0456EVAP System Small LeakP0456EVAP System Small Leak.If DTCP0456-00EVAP Purge System Small Leak.(North America only)Manufacturer communications
12Original wording in English
JEEP
Reported code forms P0456
Flash: Powertrain Control Module (PCM) Updates Customers may experience the following: ? Engine Stop/Start does not work as expected and it is often automatically deactivated. Customers may also experience a Malfunction…
JEEP
Reported code forms P0456
Flash: Powertrain Control Module (PCM) Updates **Customers may experience the following: Stop/start function deactivated.**Customers may also experience a Malfunction Indicator Lamp (MIL) illumination. Upon further…
JEEP
Reported code forms P0456-00
Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the Powertrain Control Module (PCM) with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL)…
JEEP
Reported code forms P0456-00
Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the Powertrain Control Module (PCM) with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL)…
JEEP
Reported code forms P0456
Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further…
JEEP
Reported code forms P0456
Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further…
Check vehicle applicability
2A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Historical vehicle association; OBD-II compatibility is not established by this record.
Historical records · 1 · Historical vehicle association; OBD-II compatibility is not established by this record.
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) 13, 14 ·
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.