Its a 2001 S4, it has new APR downpipes with cats and new front and rear 02 sensors.  I keep getting DTC 17522 and 17548 ( not sure on the second code ) for the rear 02 sensors have too high resistance.  Inspected all connectors and grounds, last thing I need to meter is the harness from the ECU to the 02 sensor plugs.  I can watch temp come up and voltage fluctuate once temp  hits 360*C, voltage is around 0.435 and resistance is sky high at 25.5k ohms.  If I don't find a problem with the wiring between the ECU and the 02 plugs then I suspect the ECU itself may be the problem, or I got a bad pair of 02 sensors ( unlikely but possible ) the 02's are OEM .  Resistance and voltage on the front sensors is normal, and I have a A4 30V V6 at my disposal for comparisons.  There is no tune in this car, and aside from the downpipes everything is stock.  The downpipes were installed because the originals were broken at the flex.  Also the 02 harness' are tied up out of harms way.  I am having trouble with this and could use some insight.  Keep in mind this is NOT a heater circuit code and no other codes are present.

to disable this dtc you have to zero out CLAHSH and CLAHSHE maps

Sorry guys, rather new to the coding side of things, I don't have the slightest idea of where to start with that stuff, I have been reading up on it and would like to know what I need.  Back to the code(s), I will test the wiring tomorrow I think that the sensors use a shielded cable specifically.  I am leaning towards the ECU being the problem, I should know soon.   Any other ideas??

I found that the ECU was/is the problem, monitoring the rear 02 sensor resistance with the original ECU it was shown to go straight to 25.5k ohm after the catalytic converter came up to temp.  I replaced the ECU, brought it up to temp and now it is shown as being within spec, 0.10k ohm.   This has been a thorn in my side for a few weeks and I am glad that a resolution has been found.