Reductant Quality Sensor Circuit Range/Performance
The P206B code indicates that the reductant quality sensor, which monitors the quality of diesel exhaust fluid (DEF) in the selective catalytic reduction (SCR) system, has detected a signal that is out of the expected range or performance parameters. This sensor measures the concentration of urea in the DEF to ensure proper NOx reduction. A fault can lead to incorrect DEF quality readings, potentially causing the SCR system to malfunction and increase emissions.
01. Most Common Causes
- Faulty reductant quality sensor
- Wiring or connector issues in the sensor circuit
- Contaminated or incorrect DEF fluid
- Software or calibration error in the ECM
02. Symptoms You Will Notice
- Illuminated check engine light
- Reduced engine performance or power
- Increased fuel consumption
- Possible limp mode activation
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Inspect the reductant quality sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance and voltage according to manufacturer specifications.
Step 4: Check the DEF fluid quality and level; replace if contaminated or incorrect.
Step 5: If necessary, replace the sensor and clear the code, then test drive to verify repair.
04. Commonly Affected Makes
05. 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 lead to reduced performance, increased emissions, and potential damage to 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 the sensor price and labor rates. Diagnostic fees may apply.