lambda sensor light keeps comen on?

The output signal from a Lambda sensor should vary from 0 to 1V in normal operation - it reqires the correct fuel to air ratio to achieve this (this is actualy a very ineficient way of burning fuel but thats another story!) if the output is 1V all the time this would indicate too much air is getting into the engine (or not enough fuel) if it is output is 0V then all the oxygen is being burnt (too much fuel). You need to find out what the output is? - if its not enough fuel (1Volt) check for blocked fuel filter, fuel pump etc.. if its too much (running rich) check for air leaks in the induction system, faulty idle control valve. also the O2 sensor has a built in heater so it starts to work quicker during cold starts - if this is at fault the car will probably run perfectly normaly but turn on the warning lamp! you will need an ohm / volt meter to check this, normal resistance is 5 - 10 ohms on the 2 white wires of the O2 sensor, (sometimes these are 2 grey wires?) this heater is only powered for a few minuits after starting the car

ian
August 2010