O2 Sensor trouble

[monkeybongos]

Engine code is saying “O2 sensor circuit abnormality”.
Scooter starts, idles and runs well, however mpg is down 10%.

What is the typical lifespan of an O2 sensor?
Scoot is 6 yrs old w 31,000 miles.
Is it likely in need of a new O2 wire?

[Ruffus]

@MB, usually a O2 sensor has a theoretical lifespan of 50-100.000km.
I would:
-take the sensor out (proper fitting ring spanner!)
Do NOT use rust remover or oil! Heat it up!
-check cables for any demage
-soak the sensor in fuel or alcohol for a while
-clean the cover and holes properly
-blowdry with compressed air
-put it back again
A caked sensor, be it from wrong/ too rich fuel or not reaching working temps of around 600°C due to short trips, might show such symptoms.

[monkeybongos]

The sensor was coated in white soot.  Whether due to all the miles over time or its recent malfunctioning that maybe caused the scooter to run to rich (or lean), I don't know. Soaked it in kerosene for 4 hrs, then let it dry overnight.  Looks much cleaner.

Disconnected battery to reset the engine light, but "O2 sensor circuit abnormality" still flashing.  Also code for "ignition circuit abnormality" is flashing, which I thought I fixed by cleaning the brake switch that hadn't been working  (it is now working--but engine light still flashing).  Does it typically take a while for the engine light to reset?

Recently removed the muffler twice (tire change and later to check for leak).  Did not disconnect the O2 sensor, there was a bit of stress on the cable while the muffler was sitting off to the side.  Read yesterday the sensors can be fragile, wondering if stress on the cable damaged it?  Connections look ok, no visible damage.

Thinking I should order a new O2 sensor, unless someone has other ideas.  Don't mind the $130, but if it can be avoided...
In the future I will disconnect the sensor before removing the muffler, that's for sure. 

[Ruffus]

MB, white or grayish-white is principly a good sign, means working temps were reached (~ 600°C).
No, does not take time to reset. But can, until temps are reached.

This streching of cables might cause a malfunction, for this are pretty rigid (high temp)
lines like feeler gauges.
If you have the chance to see a car shop with a CO tester, ask them to do a test on your emission.
Should be under 2% CO. Hot motor. 1.5-1.6 opti.

New sensor: there are lots of O2 sensors available online, ranges from  €15,- to €50,-
Watch for the cables and the correct thread/lenght.
If you have two cables on your sensor, take such.
If you have three or four and within those a red one, means your sensor is heated.
Pls see pic as an example...

Multimeter check: a guesswork but...
-cold sensor zero conductivity
-hot sensor conductivity
Like said, inexpensive ones available.