I am attempting to repair a 1999 Mercedes ML430 for emissions failure. The diagnostic codes are PO 141 and PO 161 - O2 sensor heater circuits; bank 1, sensor 2 and bank 2, sensor 2.I have replaced both post-converter sensors and repaired the wiring harness to the left bank that was corroded. I cleared the codes. Ran a drive trace. Code PO 141 and 161 returned. Double checked power and ground to each sensor; open loop and closed loop. Found no problems; cleared the codes again. Ran drive trace. Same codes returned. Also, EGR monitor did not set. Wondering if re-flashing the ECM would help? Any who may have an insight to this problem I am very interested in hearing your suggestions. Thank you.