Finally let the error read.../ 537 Lambda...

Hello.

I finally had my mistakes read out today. I already had problems with too high consumption (24.0 l / city). I thought you could just drive to ATU to read the bugs... So according to the printed protocol, error 537 - Lamda control (before Kat) - signal appears faulty. Additional information from the control unit to the error code: rule limit exceeded. Additional error 516 throttles-empty switch - signal faulty. Additional information from the Steurger to the error code - Interruption Short circuit after plus. Hope I can rely on the evaluation of ATU. Because everything didn't look so trusting. (Mechanic closes the car instead of using IR-FB, takes three attempts to start it and I waited a good hour until you were finished with the "read out"...) Does anyone know what the original lambda probe costs? Since there are obviously divided opinions about Unifit-Lambda ́s. For DuW-Repair, the costs of NGK 114 Euro and Bosch 122 Euro. Can anyone recommend something? Thank you in advance...
MfG Andi K.