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O2 sensor voltage change

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cps13

Original Poster:

232 posts

89 months

Saturday 31st March 2012
quotequote all
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

1,724 posts

119 months

Saturday 31st March 2012
quotequote all
if its got 2 sensors they should both keep switching!

Gaspode

4,112 posts

103 months

Saturday 31st March 2012
quotequote all
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

12,244 posts

108 months

Saturday 31st March 2012
quotequote all
It's normal behaviour for working O2 sensors.

stevieturbo

11,606 posts

154 months

Saturday 31st March 2012
quotequote all
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

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eliot

6,904 posts

161 months

Saturday 31st March 2012
quotequote all
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

1 posts

51 months

Wednesday 11th April 2012
quotequote all
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 ;-)