P2045 indicates that the powertrain control module has detected a high voltage condition in the reductant (urea) temperature sensor circuit, meaning the sensor is reporting a temperature that is unrealistically high or the circuit voltage is out of range.
The sensor itself may have failed open or shorted, sending an out‑of‑range voltage to the PCM.
Corroded pins, broken wires, or loose connectors in the sensor circuit can cause high voltage readings.
A short to battery voltage (12 V) in the wiring or connector can raise the sensor signal voltage above the acceptable range.
Incorrect sensor type or improper mounting can produce erroneous temperature signals.
A rare case where the PCM's input stage for the sensor is damaged, but this is far less common than sensor or wiring issues.
It is possible but uncommon. In the vast majority of cases the problem is the sensor, its wiring, or a short to voltage. Replace the PCM only after confirming the sensor and circuit are functioning correctly.
If the sensor is out of specification or has failed, replacement will usually clear the code. However, the wiring and connector must also be inspected to ensure the new sensor receives a proper signal.
Yes. The SCR system relies on accurate reductant temperature data to control urea dosing. A high‑temperature sensor reading can cause improper dosing, leading to elevated NOx emissions and a failed test.
Because the PCM processes the sensor signal, some may assume it is at fault. This advice is often misguided; sensor and wiring faults are far more likely and should be ruled out before considering PCM replacement.