LEXIA O2 graphs

The Check Engine Light on my C3 has come on and I'm having trouble fault finding.
The fault is associated with the upstream O2 sensor but I am getting sensible instantaneous readings! The question is what is the engine ECU whinging about if it says there is a fault when it is getting a signal from the sensor?
I can get the instantaneous voltage readout but I was wondering if LEXIA will provide a continuous graphical read out? While driving around it's impractical to look at the screen all the time. So my theory is that I might be missing intermittent losses of signal. A continuous graphical output might catch a loss of signal.
I might be missing something but I cant find a way of displaying the O2 sensor as a continuous graph.

All of this might be for naught because the light only comes on at start up, not during a drive. I reset the light and the car drives for about 24 hours without the light coming on. Start, stop, start, stop, no problems. Then on the next day, the light comes on!
I thought it might be the connector (I'm not suspicious of the sensor itself I think that's OK) so I changed the sensor but still the same. So it leaves the wiring (and connectors) or the engine ECU.
My rhetorical question is why does the light come on at start up and not while the car is running? Why the next day and not straight away?

Ozvtr wrote: ↑Mon Aug 10, 2020 10:54 pm The question is what is the engine ECU whinging about if it says there is a fault when it is getting a signal from the sensor?

Lexia will give you a code and a description when you scan for faults, what is the code it gives for you?

A screen shot save a lot of typing


I had a wheel sensor that showed a permanent fault, but gave the same, correct speed reading as the other wheels. The sensor and mag ring needed a clean and the fault cleared. So, the system can detect faults but the data looks good.

You can also have the default data from the ecu map making things look odd. Disconnect the MAF and you can get default 'live' data calculated from the map that can't possibly from a disconnected sensor.

C3CAR wrote: ↑Tue Aug 11, 2020 9:50 am A screen shot save a lot of typing

I'll be home late tonight so I wont be able to give you that 'till later in the week.

C3CAR wrote: ↑Tue Aug 11, 2020 9:50 am I had a wheel sensor that showed a permanent fault, but gave the same, correct speed reading as the other wheels. The sensor and mag ring needed a clean and the fault cleared. So, the system can detect faults but the data looks good.

Do you have any sort of theory for this one? Data Ok but low magnitude causes a fault?

C3CAR wrote: ↑Tue Aug 11, 2020 9:50 am You can also have the default data from the ecu map making things look odd. Disconnect the MAF and you can get default 'live' data calculated from the map that can't possibly from a disconnected sensor.

OH! That makes sense and is disturbing at the same time! Phantom MAP sensor syndrome? LOL! Something to remember.

So, no way of displaying a graph?

With the current laptop it won't playback a graph because the 'graphic processor is not compatible' or some such. But it will show it all on screen as I drive, not great for safety. I need to upgrade the lexia laptop for full functionality.

So where is the option to display a graph in LEXIA?

I found out you can make graphs but not live. It records the data and then when you stop the recording it displays the graph You need to go into custom parameters, then select the parameters you wish to monitor, then F6 to create a recording.