Hi Tony, where are you measuring the voltage at? Only asking this as all info I can find refers to titania having a high resistance when weak, and given that a voltage is supplied to the sensor, then the output voltage would reduce when weak BUT some ecu's I have read about compare this to a referance voltage and then use the result as the relevant voltage. Eg 5 volts in and weak mixture = high resistance = say 1.5 volts out which is then compared to referance voltage of 5 volts = 3.5. This could create an oposite depending on whether you measure from the sensor or from live data.