O2B Voltage / O2Bv Behaviour
Posted: Sat Jul 19, 2025 1:01 pm
Hi,
Just wondering what a "normal" readout looks like for the O2B voltage, in this case the 2016+ turbo civic.
Quick background; I've had a custom tune for years with zero issues, Ltrim never strays a couple percent from zero. Just recently, I pulled up the app to see it at -3%. Over a couple days this eventually became -12%. The engine "feels and sounds healthy", I can't imagine any mechanical reason it would need to pull so much fuel (but I am welcome to ideas!). Brand-new O2 sensor yields no different. Pressurized everything from the inlet pipe, nothing leaking on the outside.
However, I noticed one sensor that appears on the app, but not in datalogs: "O2Bv". The only mention of this in the documentation is on a table of supported sensors but that "not all sensors can be datalogged from every ECU". When viewing this sensor live, the value jumps back and forth from 0.0v to 5.0v, and sometimes settles around 4.7v around idle and 3.0v under throttle. On a cold start, this value is pretty stable, but after a few minutes it becomes sporadic again. If I were to take an educated guess, something is warming up, faulting out, and the ECU might be averaging this as a lower voltage than normal, and pulling fuel in response.
So, my question here is; is it normal for the O2B voltage to jump all over the place rather than be a relatively consistent reading?
The only other mention of this sensor online is here where someone is experiencing the same symptom with no answer. I also can't refer to previous datalogs because the sensor isn't recorded... I've attached two new ones anyways in case it helps, and a video of the sensor value jumping all over the place is here. Any information about this would greatly help in knowing if air is somehow escaping or if I have an electrical issue!
Just wondering what a "normal" readout looks like for the O2B voltage, in this case the 2016+ turbo civic.
Quick background; I've had a custom tune for years with zero issues, Ltrim never strays a couple percent from zero. Just recently, I pulled up the app to see it at -3%. Over a couple days this eventually became -12%. The engine "feels and sounds healthy", I can't imagine any mechanical reason it would need to pull so much fuel (but I am welcome to ideas!). Brand-new O2 sensor yields no different. Pressurized everything from the inlet pipe, nothing leaking on the outside.
However, I noticed one sensor that appears on the app, but not in datalogs: "O2Bv". The only mention of this in the documentation is on a table of supported sensors but that "not all sensors can be datalogged from every ECU". When viewing this sensor live, the value jumps back and forth from 0.0v to 5.0v, and sometimes settles around 4.7v around idle and 3.0v under throttle. On a cold start, this value is pretty stable, but after a few minutes it becomes sporadic again. If I were to take an educated guess, something is warming up, faulting out, and the ECU might be averaging this as a lower voltage than normal, and pulling fuel in response.
So, my question here is; is it normal for the O2B voltage to jump all over the place rather than be a relatively consistent reading?
The only other mention of this sensor online is here where someone is experiencing the same symptom with no answer. I also can't refer to previous datalogs because the sensor isn't recorded... I've attached two new ones anyways in case it helps, and a video of the sensor value jumping all over the place is here. Any information about this would greatly help in knowing if air is somehow escaping or if I have an electrical issue!