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, is reporting a signal that is out of the expected range or not performing correctly. This sensor measures the concentration of urea in the DEF to ensure proper NOx reduction. A range/performance issue suggests the sensor's output is either stuck, slow to respond, or reading outside normal parameters, often due to contamination, wiring faults, or sensor failure.
1. Most Common Causes
- Faulty reductant quality sensor
- Contaminated or incorrect DEF fluid
- Wiring or connector issues in the sensor circuit
- SCR control module malfunction
2. Symptoms You Will Notice
- Illuminated check engine light
- Reduced engine performance or power
- Increased emissions or failed emissions test
- Possible limp mode activation
3. 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 wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the DEF fluid quality using a refractometer or sensor-specific tester to ensure proper urea concentration.
Step 4: If wiring and fluid are okay, replace the reductant quality sensor and clear the code.
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 lead to reduced engine performance, increased emissions, and potential damage to the SCR system. In some cases, the vehicle may enter limp mode, limiting speed and power.
How much does it cost to fix?▼
The cost to fix P206B typically ranges from $50 to $150 for diagnosis and sensor replacement, depending on labor rates and parts costs. The sensor itself is usually between $30 and $80.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.