Kia Optima Hybrid Owner's Manual Quiz
Emission Control System

Natural Vacuum Leak Detection (NVLD) Description and Operation

In this manual: Emission Control System
General Information — 4Engine Mechanical System — 50Engine Electrical System — 20Emission Control System — 30Engine Control System/Fuel System — 84Automatic Transmission — 98Drive Shaft and Axle — 15Suspension System — 36Steering — 12Restraints — 50Brake System — 38Body (Interior and Exterior) — 54Body Electrical System — 233Heating, Ventilation, and Air Conditioning — 57
~1min read

Description

The Natural Vacuum Leak Detection (NVLD) is located between the canister and the fuel tank air filter. The NVLD detects leaks equivalent to a 0.5 mm hole in the fuel tank, canister and hoses. When the engine has been running, the fuel temperature in the fuel tank is slightly elevated. When the engine is turned off, the fuel temperature should drop. The ideal gas law states that in a sealed system, the pressure drops in proportion to the drop in temperature.

[No Leak]

[Leak 0.5 mm]

While the engine is off, the ECM monitors the pressure switch built into the NVLD to detect a small pressure drop. If no switch change is detected after the engine is stopped, it is assumed that there is a leak in the sealed system.

Test yourself

A quick Kia Optima Hybrid Owner's Manual quiz: every answer comes with an explanation and a link to the manual page.