Lambda sensor

I am trying to get some good/ concrete info on lambda sensor ( o2 sensor) and lambda ratio. I work on a bunch of honda vehickes and run into this data pid on scan tool both in factory and global obd2. I wanted to verify the my understanding so I can sure that the data i see matches what it actually means. Sorry if this is too back to basics type question but I'd rather ask the question instead of make a mistake with a customer. Thank you all for all the help and info.

Not too back-to-basics at all! Just to be clear, are you referring to air/fuel ratio sensor, or conventional oxygen sensors?

I usually see the Lambda PID associated with Honda's equipped with air/fuel ratio sensors. I've always understood it to be a direct representation of the mixture measured in the exhaust. 1.00 represents stoichiometric, higher indicates lean, lower indicates rich. Here's a known good capture that I posted in the air/fuel ratio testing thread .

www.scanshare.io/share/ZsdIdUM6zkK47APTf-fFqw#0,2,3,4,5,42,43



In this capture, the cursor marks wide open throttle fuel enrichment. Hope this helps!

Tyler wrote: Not too back-to-basics at all! Just to be clear, are you referring to air/fuel ratio sensor, or conventional oxygen sensors?

I usually see the Lambda PID associated with Honda's equipped with air/fuel ratio sensors. I've always understood it to be a direct representation of the mixture measured in the exhaust. 1.00 represents stoichiometric, higher indicates lean, lower indicates rich. Here's a known good capture that I posted in the air/fuel ratio testing thread .

www.scanshare.io/share/ZsdIdUM6zkK47APTf-fFqw#0,2,3,4,5,42,43

In this capture, the cursor marks wide open throttle fuel enrichment. Hope this helps!

Yes Tyler it was a/f sensor on bank 1 of a 05 pilot. It throw a the occasional p0420 so I was trying to figure out why it occur so randomly. So I began looking at all the fuel related pids which lead to me posting here. Thanks this confirmed what I thought after watching them and performing a few snap throttles. Thanks for the Info. Always a great experience here on the forum

Great to hear, thanks!

It sounds like the catalyst on bank one is on the failure borderline... Here's an example I took off an '07 Jeep Patriot. It was intermittently flagging a P0420, and this is the Mode $06 result it came in with:



Before any testing, I cleared the codes and took it for a drive. I got the catalyst monitor to run again, and this is what I found:



Catalyst, make up your mind! Are you working or not? :lol:

I have a follow up question to this one, I hope you don't mind me posting here knoxTech.
On a Honda with an upstream AFR and downstream zirconia sensor, (an 05 civic EX) how is B1S2 fuel trim calculated, and how much weight does it have on
AFFB(short term) and AFFB AVG(long term)?
Does this PID hold any real diagnostic value?