January 18, 2019
Understanding & Live Graphing of the Rear O2 Sensor: OBD4Everyone Ep.19
On this episode of OBD4Everyone we are going to explain and show everything you need to know about the rear o2 sensor AND show you how to use OBD Fusion’s LIVE graphing feature.
Reading Engine Trouble Codes with OBD Fusion for iOS: OBD4Everyone Ep. 10
Reading Engine Trouble Codes with OBD Fusion for Android: OBD4Everyone Ep. 11
OBD Fusion’s Enhanced Diagnostics Setup and Use: OBD4Everyone Ep.16
About Author
Frank from OBD4Everyone.ca
Frank has been studying on-board diagnostic (OBD) systems since 1998. He is now on a mission to show how useful it is to everyone, hence OBD4Everyone.ca
2 Comments
Maybe I’m missing something but every other reference about output voltage for the REAr O2 sensor states the the output should not oscillate the way it is shown in your video. In fact other articles specifically state that if the rear O2 does oscillate it means the Cat is not working. BTW excellent production and a great script. Please help me understand what is going on…
Hi George,
Thanks for your kind words!
The rear o2 sensor will always oscillate/switch between lean and rich regardless of the catalytic converter performance.
The biggest difference is the frequency of the switching.
If the rear o2 sensor oscillates at a frequency similar to the front o2, the catalytic converter performance is very low.
A properly function catalytic converter will have a high oxygen storage capacity and result in a slower switching rear o2 sensor.
A general rule if thumb is the rear o2 sensor should switch about ever 1-3 seconds for a healthy catalytic converter.
Here is a good article that gives more details:
https://www.discountconverter.com/tech-tips/news_page.cfm?Key=catalytic_converter-&News=218