Related to GenBoard/Manual/WBSensorControllerTesting
For pump current=0mA, Bosch datasheet says lambda =1.027 (1.03 can be displayed, maybe 1.04, there is always some margin in measurements).
Some other devices display 1.00 (or 0.99) for the same circumstances.
We recommend tuning the LSU4 to Bosch specs (regardless of other vendors; the "real" value is very complex to measure).
One can of course change the bias with pump_pw_zero dutycycle (by 2..3 points, instead of the calibration around 101 typical that one can verify - and should in case of any doubts or old ECU of unknown history).
Or compensate simply with lambdatarget. (even vemstune ini can be adjusted to show as one likes).