In addition to the good advice of others here about CPS operation, good signal and good contact, premature CPS failure can be due to premature failure of the protective cable insulation and foil shielding. Low quality cable construction and a harsh engine operating environment can speed the demise of a cheap CPS. Engine twist and vibration flexes the cable. Volvo uses plastic standoff clips on the water pump return line behind the block both to keep the cable from abrading against the return line and firewall, and just as important to move the cable flex point from the sensor on top of the bell housing (a vertical flex point) to the cable section between the firewall clip and the upper standoff (a horizontal twist flex). If the clips are missing (NLA from Volvo) then you can try fashioning your own using a figure 8 plastic zip tie (UV proof, thick one) through a stub of vinyl or rubber tubing as the standoff.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now