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Fast Idle - Rear O2 Sensor issues
After a couple of weeks of ownership of my 2006 V70R, I dropped it into the local Volvo specialist for a check over. They discovered an issue holding a fast idle. When revved to about 2500 and held, it drops the revs to 2100 quickly, then returns. This fluctuation continues every second or two. They diagnosed a possible issue with the Cat.
There are no relevant codes in VIDA, just a couple related to the A/C not working, which I know about. There only other symptom I have is it smells a bit 'fuelly', but I don't know what a 16 year old V70 should smell like.
I've tried to test it using VIDA, but don't know enough about fuel trims and O2 sensors to diagnose reliably.
https://youtu.be/NmrOjE5Ie7Y
The initial sharp fluctuations in the rear sensor (blue line) show what's happening with the symptoms in the video. The second half of the trace is under normal idle. I think this is normal behaviour, but not 100%. Can anyone help explain what's going on here? Should the reading from the front O2 sensor be so flat?
Attachment 33117