Near zero emission levels from an internal combustion engine were achieved to meet California’s Partial Zero Emission Vehicle (PZEV) requirement beginning with the 2003 model year. Using a systems approach, the tailpipe emission requirements for the PZEV standard were cascaded to the base engine design, control system and catalyst system to achieve the engine-out emissions and catalyst efficiency requirements. Major emphasis was on low emission cold starting and rapid catalyst light-off. Overall catalyst efficiencies of over 99.9% for hydrocarbon emissions, 98.8% for carbon monoxide emissions and 99.5% for oxides of nitrogen emissions were achieved over 150K miles. In addition to achieving near zero levels for tailpipe emissions, on-board diagnostics were developed to detect malfunctions in the near zero emission control systems. Likewise, a near zero evaporative emission system was developed. Future PZEV developments are described as more vehicles will be required to meet the PZEV requirements in the future.

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