oxygen sensor query

Ask any questions about using PicoScope Automotive software here.

oxygen sensor query

Postby PeterM » Mon Nov 09, 2009 4:06 pm


If a zirconia o2 sensor complete waveform is biased towards the rich [low in o2] in closed loop and the ecu leans out to maintain the A/F ratio, how come the o2 waveform appears to stay the same i.e. still showing a rich reading at a steady 1500rpm.

Appreciate any help offered.

Posts: 9
Joined: Fri Jun 26, 2009 2:51 pm
Location: Saddleworth

Re: oxygen sensor query

Postby Matt Fanslow » Mon Nov 09, 2009 4:43 pm

Can you verify with an exhaust gas analyzer that the trim adjustment "worked"?
User avatar
Matt Fanslow
Posts: 15
Joined: Wed Aug 01, 2007 8:38 pm
Location: MN

Re: oxygen sensor query

Postby Autonerdz » Mon Nov 09, 2009 4:48 pm

Hi Peter,

Not sure I fully understand the question. Is the O2 voltage always high, or does it switch normally and just spend more time high than low?

If it is still switching but biased high by spending more time high than low, this could be normal strategy.

If it is high and not switching, even with fuel trims negative in closed loop, then probably the O2 has a problem or the PCM can't compensate.

Tom Roberts
(The Picotologist)
skype: autonerdz
THE PicoScope Automotive Authority
In North America
User avatar
Zen Master
Zen Master
Posts: 268
Joined: Wed Nov 20, 2002 4:19 pm
Location: Washington State USA

Return to PicoScope 6 Automotive software

Who is online

Users browsing this forum: No registered users and 0 guests