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O2 sensor voltage change

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cps13

Original Poster:

234 posts

95 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

1,785 posts

125 months

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

Gaspode

4,112 posts

109 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

13,043 posts

114 months

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

stevieturbo

12,065 posts

160 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

7,229 posts

167 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

57 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 ;-)