Reductant Temperature Sensor Circuit High
The P2045 code indicates that the reductant temperature sensor circuit, which monitors the temperature of the diesel exhaust fluid (DEF) in the selective catalytic reduction (SCR) system, is reporting a voltage higher than the expected range. This sensor is critical for proper DEF dosing and emissions control. A high circuit voltage typically points to a short to power, open ground, or a faulty sensor. If left unresolved, it can lead to reduced engine performance, increased emissions, and potential limp mode activation.
1. Most Common Causes
- Faulty reductant temperature sensor (internal open circuit)
- Open circuit in sensor signal wire (broken or disconnected)
- Signal wire shorted to battery voltage (12V)
- Sensor connector corroded, loose, or with damaged terminals
- Internal PCM failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Increased diesel exhaust fluid consumption
- Poor fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the reductant temperature sensor and wiring for damage, corrosion, or loose connections.
Step 3: Using a multimeter, check the sensor signal voltage (should be 0.5-4.5V at operating temp). If voltage is near 5V, suspect a short to power.
Step 4: Test the sensor resistance (refer to manufacturer specs). Replace if out of range.
Step 5: Check for continuity in the ground circuit and repair if open.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can cause the vehicle to enter limp mode, reduce fuel efficiency, and potentially damage the SCR system. Immediate diagnosis is advised.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the sensor or wiring needs replacement. Sensor replacement is usually straightforward.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.