This panda has the indicated error stored in the ECU as sporadic, if I delete it it reappears even after a month.. The diagnostics in my possession (Bosch and Div0) do not allow me to display the voltage value of the upstream lambda sensor in the control unit parameters, but I can read it from the obd reading on the Bosch (I hope it's reliable) and it would seem to cycle around volts (hot engine) while the downstream one remains stuck at 0.750 (to see it properly it would take an oscillo, I know). This is an error I sometimes get on LPG cars (often due to switching delays) but this is dry petrol. By the way it's got 12000km real so reasoning about valves and ignition system is possible but not probable.. is there any sw update maybe? Upstream lambda sensor 'poisoned'? Apart from the malfunction on (and start&stop not available) the car seems to run fine, only when cold does it smell a bit like unburnt petrol but maybe it's an impression.