Natural Vacuum Leak Detection (NVLD): Notes
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Natural Vacuum Leak Detection (NVLD) is a passive diagnosis system for the fuel evaporation system.
The NVLD requires a longer engine cutout time in order to identify a leakage. Therefore a short leakage test is not possible. Depending on the ambient conditions, the diagnosis normally requires that the engine is off for between 6 and 12 hours.
The California Air Resources Board (CARB) has issued a regulation. This regulation states that an overall leakage in the fuel evaporation system exceeding 0.51 mm (0.02 inches) must be identified.
The fuel evaporation system must therefore meet the following requirements:
- Sealed against the environment
- Identify and display a leak
NOTE:
USA and Korea national-market versions!
The leak diagnosis on the fuel tank for petrol engines is a legal requirement in these countries.