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Most current automotive and light truck fuel level sensors are essentially rotary potentiometers that have been designed to survive the chemically harsh environments found in the fuel tank. This paper will chronicle the design improvements made from the early wire wound versions to today's more robust thick film ink systems. The paper will highlight potential failure modes and discuss techniques to reduce noise and increase wear life. Data will be provided regarding changes in the circuit layout, ink compositions, and contact materials. Special consideration will be given to the adverse effects associated with the reactive sulfur prevalent in today's fuels.

Close coupled catalysts and new ceramic catalyst substrates have significantly improved the light-off performance of automotive converters required to meet stringent emission requirements. The hotter environment of these catalytic converters and the lower structural strength of the ceramic substrates require the rethinking of converter designs. The development of new package requirements to accommodate the change in environment and new substrates are discussed. A historical perspective on converter durability is presented as reference. Development of durability test protocols is essential to verifying product durability performance to these new environments. Data collection and documentation of testing templates are shown to demonstrate the effectiveness of tests that represent real world environments. Design improvements to address failure modes are discussed along with durability improvement results.