i have slightly different values for a double sensor failure, if you have a single failure or shortcircut in either sensor the ecu applies the following.

with ats failure and cts < 47'c...... ats value is set equal to cts value
with ats failure and cts > 47'c...... ats value is set at 47.5'c

with cts failure and ats < 30'c...... cts value is set equal ats value
with cts failure and ats > 30'c...... cts value is set at 90'c

with a double sensor failure the values applied by the ecu are.. ats 47.5'c and cts 90'c

i not sure if this is for L1-6, L8, P8 or all of them. if all else fails replace both to be sure to be sure.