P205A: high reductant-temperature signal can represent an open circuit

P205A concerns the reductant tank-temperature sensor circuit. Audi's CPNB table lists both a short to battery voltage and an open circuit, with sensor signal above 4.63 V. The shared threshold is important because the code does not distinguish those two physical conditions by itself.

High feedback does not establish hot fluid

The criterion is expressed in volts, not degrees. As diagnostic interpretation, it cannot be translated into a conclusion that the reductant tank overheated. The signal may be unreliable precisely because the circuit is open or connected to an unintended electrical potential.

Nor does the row prove which component should be replaced. A sensor, its connection and the circuit architecture need the appropriate vehicle-specific evaluation before the high-signal finding can be attributed to a physical defect.

Use temperature and circuit evidence appropriately

The source supplies no voltage-to-temperature curve, connector assignment or normal tank-temperature range in this row. Those omissions matter when comparing a scan value with a workshop measurement. A useful diagnosis explains the electrical condition before relying on the reported temperature for other decisions. This monitor description belongs to the CPNB section of the 2014 Audi A6/S6 reference book and is not a universal test for every reductant-temperature sensor.

Source: Audi 2014 A6/S6 Quick Reference Specification Book.