2011 Honda Fit Sport, 187,000 miles.
Code P0138: Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2.
A friend of mine has a OBD port that can do live data but is new to understanding how to read it and what the numbers mean.
I looked at the live data myself for Bank 1 Sensor 1 and the graph line fluctuates like you show on your YouTube channel.
Bank 1 Sensor 2 live data shows a pretty consistent flat line although there are periodic minimal fluctuations so I assume it’s bad.
The reader shows a probability of 38% maybe a bad cat, and this sensor is after the cat.. so could it be that?
Would a bad cat give the Sensor 2 a code..? Would the graph ever be like 95% flatlined and it’s like that because of a bad cat, or would the graph show it still fluctuating like normal?
I pray it’s just the oxygen sensor based on the poor data I seen and the cat is ruled out.
Thank you so much if you answer Scotty or anyone else for their input.
😳
Check the connections for the sensor. If all checked out, it is time to change the O2 sensor.
Thank you so much!
The O2 sensors will always read ups and downs, if it shows a stable flat line, something is up. High voltage from O2 sensors means the sensor is reading rich air/fuel ratio. However if it's flat, this could be either the sensor is bad, the cat is done or the obd scan tool your friend has is not precise enough to read live data faster than one second, and instead is reading an average, which should be around the middle.
Here's something you should try:
Plug your scan tool and look at live data, try to see if the flat line is at 1V or around 0.9V. O2 sensors will range from 0-1V, however in the real world it's mostly from 0.1V to 0.9V ish, it will never reach full 1V. If it shows full 1V flat, that means the O2 sensor has an open circuit or a short.
If not, your cat is shot. To answer your question, yes a bad cat will pop up the check engine light and give a code, the 2nd O2 sensor's one and only job is to ensure that the catality converter is working, if it's sending high information but the circuit is fine then the cat is at fault and needs to be replaced.
