Tests Zirconia and Titania lambda sensors and ECU. Suitable for 1, 2, 3 and 4 wire sensors, heated and unheated. LED display shows crossover signal from sensor. Simulates rich or lean mixture signals to check ECU response. Insulation-piercing clip for quick and easy connection plus display to confirm wire identity. Powered by 9V battery (not supplied) and has low battery indicator.