P2044 indicates the powertrain control module has detected a voltage signal from the reductant (Diesel Exhaust Fluid) temperature sensor that is below the calibrated minimum threshold. This typically signals a short to ground in the sensor, wiring, or connector, or a failed sensor element. The code sets when the PCM interprets the low voltage as an implausibly high temperature or detects a direct circuit fault.
The thermistor or sensing element inside the DEF tank or line has failed electrically, creating an internal short circuit that pulls the signal voltage to near zero.
The signal wire or reference voltage wire is chafed, melted, or corroded, making contact with the vehicle frame or another ground source between the sensor and PCM.
Moisture, DEF crystallization, or poor sealing in the sensor connector creates a conductive path between the signal circuit and ground.
While rare, frozen or contaminated fluid could cause unusual readings, though this typically triggers rationality codes rather than circuit codes; crystallized DEF around the connector can also cause shorts.
Rarely, the PCM's internal analog-to-digital converter or pull-up circuit fails, misreporting a normal sensor voltage as low; this should only be considered after verifying wiring and sensor integrity.
Operation is typically limited; many vehicles will activate a derate (reduced power) strategy within a set number of miles or engine hours, and some may eventually prevent restarting until repaired.
Not usually; the temperature sensor is often available as a separate service component, though some designs require tank replacement if the sensor is integral and non-serviceable.
It is highly unlikely; the reductant temperature sensor and its wiring are the cause in the vast majority of cases. PCM replacement should only be considered after exhaustive circuit testing confirms the module is not reading a correct voltage that is present at its connector.
No; if the circuit fault persists, the code will return immediately or after the next monitoring cycle. Clearing is only useful for verification after physical repairs are completed.