Abstract: The intermediate positions of a carburetor choke valve between fully open and closed positions are registered during engine operation by illumination of light emitting diodes on a dash mounted indicator to warn the driver of incomplete opening of the choke valve after initial cold engine start-up. Signal generating photocells supply the position signals to the indicator under control of a masking plate restrictively directing illumination from a source to one of the photocells. A linkage assembly connects the choke valve to the masking plate for movement thereof to positions corresponding to choke valve positions.