What Does P2045 Mean?
The reductant (DEF/urea) temperature sensor is reporting a voltage signal higher than expected. This indicates an electrical fault in the sensor circuit rather than an actual temperature problem.
Common Causes
35%
Shorted reductant temperature sensor or internal sensor failure
30%
Damaged wiring harness with short to voltage between sensor and ECM
20%
Corroded or damaged connector pins at sensor or ECM
10%
ECM internal driver circuit failure
5%
Aftermarket DEF system components causing voltage interference
Diagnostic Steps
1
Step 1: Inspect reductant temperature sensor connector for corrosion, damage, or moisture intrusion
2
Step 2: Measure voltage at sensor connector with key on, engine off - should read approximately 5V reference
3
Step 3: Check resistance of reductant temperature sensor per manufacturer specifications
4
Step 4: Inspect wiring harness from sensor to ECM for damage, chafing, or signs of shorting
5
Step 5: If all wiring and sensor test good, suspect ECM internal fault
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The reductant (DEF/urea) temperature sensor is reporting a voltage signal higher than expected. This indicates an electrical fault in the sensor circuit rather than an actual temperature problem.
The most common cause of P2045 (Reductant Temperature Sensor Circuit High) is: Shorted reductant temperature sensor or internal sensor failure
Typical repair costs for P2045 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive short-term but may enter limp mode or derate. Extended operation may cause SCR system damage and emissions violations.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2045 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control - SCR System
Difficulty
Type
Generic (SAE)
Recommended Tools
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