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 pumppw_zero dutycycle

* pumppw_zero + 3 (instead of the actual ECU pumppw_zero value) will show 0.02 lower lambda around 1.00

** pumppw_zero + 4 would show 0.027 lower lambda around 1.00 (like when neglecting Bosch datasheet lambda=1.027 @Ipump=0mA, and showing 1.00 to match some other measuring equipment ). However, deviation of more than 3 is not recommended.

** note that value around lambda=0.8 (and other end, in free air) are basically not effected (because of free air calibration)

** actual ECU pumppw_zero value is saved in the ECU at manufacturing (and on paper), typical appr 101, one can verify according to GenBoard/Manual/WBSensorControllerTesting (one should verify in case of any doubt or old ECU of unknown history).

* Or use lambdatarget accordingly (assuming 1.027 shown for Ipump=0mA). (even vemstune ini can be adjusted to show as one likes, even arbitrary values like AFR; although this is not recommended).