O2 sensor voltage change

[cps13]

Hi all,

does anybody know if it is normal for a pre-cat O2 sensor to have the voltage fluctuate from around 0.3-0.7V whilst idling?

Cheers

[pk500]

if its got 2 sensors they should both keep switching!

[Gaspode]

I think the standard voltage for correct stochiometric ratio is 0.47 volts, which implies that your car is wavering from slightly rich to slightly lean and back again. Do you know what the MAF signal is doing at the same time? If the idle revs are steady I wouldn't worry too much.

[Magic919]

It's normal behaviour for working O2 sensors.

[stevieturbo]

cps13 said:

Hi all,

does anybody know if it is normal for a pre-cat O2 sensor to have the voltage fluctuate from around 0.3-0.7V whilst idling?

Cheers

It is quite normal and a sign that everything is working when the lambda signal switches either side of stioch ( approx 0.5v ) with regular frequency. ie a few times a second

Actually a helpful site here

http://www.lambdapower.co.uk/diagnosis/diagnostic_...

Edited by stevieturbo on Saturday 31st March 22:00

[eliot]

cps13 said:

Hi all,

does anybody know if it is normal for a pre-cat O2 sensor to have the voltage fluctuate from around 0.3-0.7V whilst idling?

Cheers

The average those values is .5v which is stoichiometric. Which is what you would expect. narrow band sensors dont tend to really output .5 volts, they just fluctuate (or 'cross' ) the midpoint rapidly which indicates lamda.

[nijunge]

I alwais heard that you should keep the engine running at arround 2300 rpms to see the right signal from the lampba ?

We are doing a OBD diagnostic device via smart phone and include Lampda test so we are always looking for improvements ;-)