Fuel quality sensor associated with a housing in fuel delivery system

An apparatus monitors at least one fuel quality characteristic of fuel passing through a fuel delivery system of a motor vehicle. The apparatus includes a fuel rail assembly connectable to the fuel delivery system of the motor vehicle. A fuel rail assembly has at least one housing associated with either a pressure regulator or an accumulator. A sensor is associated with the fuel rail assembly for measuring at least one characteristic of fuel quality of fuel passing through the fuel rail assembly. At least one characteristic includes temperature and/or impedance. The sensor can include a pair of plates spaced from one another by a gap of between approximately 0.5 mm to approximately 1.0 mm, inclusive, for measuring impedance across the gap.