Reductant Tank Temperature Sensor Circuit Range/Performance
The P205B code indicates that the reductant tank temperature sensor circuit is out of the expected range or has a performance issue. This sensor monitors the temperature of the diesel exhaust fluid (DEF) in the tank. The powertrain control module (PCM) uses this data to manage the DEF injection system for emissions control. A fault can lead to incorrect DEF dosing, potentially causing increased emissions or triggering a check engine light.
01. Most Common Causes
- Faulty reductant tank temperature sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor or PCM
- Contaminated or low-quality DEF fluid affecting sensor readings
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased emissions or failed emissions test
- Possible DEF system warnings on dashboard
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Visually inspect the sensor and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor resistance and compare to manufacturer specifications.
Step 4: Check the DEF fluid level and quality; replace if contaminated.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive short distances, but continued driving may cause reduced performance or limp mode. It's best to diagnose and repair promptly to avoid potential emissions issues.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the sensor price and labor rates. DIY replacement can be cheaper if you have the tools.