Long-Term Aging of NOx Sensors in Heavy-Duty Engine Exhaust

Research has shown that there are many factors that affect the long-term performance of nitrogen oxides (NO_x) control systems used in diesel engine applications. However, if the NO_x emissions can be accurately monitored, it might be possible to restore performance by making adjustments to the control systems. This paper presents results from a study that tested the durability of 25 NO_x sensors exposed to heavy-duty diesel exhaust for 6,000 hours. The study, conducted by the Advanced Petroleum-Based Fuels - Diesel Emission Controls (APBF-DEC) project, tested the sensors at various locations in the exhaust stream.