P207FPowertrain
Powertrain · SAE
SCR Reductant Quality (AdBlue/DEF) Insufficient
Meaning
The SCR (Selective Catalytic Reduction) system has detected that the quality of the reductant (AdBlue/DEF, 32.5% urea solution) is below minimum requirements. The urea concentration is too low (diluted with water) or the fluid is contaminated, compromising NOx reduction efficiency.
Common causes
- AdBlue diluted with water or urea concentration below specification (< 31.8%)
- AdBlue contaminated with fuel, oil, or other fluids
- Tank filled with a non-compliant product (not ISO 22241)
- Defective reductant quality sensor (NH3/NOx or concentration sensor)
- AdBlue degraded by prolonged storage or exposure to high temperatures
Symptoms
- AdBlue or check engine warning light on
- Dashboard warnings related to reductant quality
- Power reduction or engine shutdown (after repeated uncorrected warnings)
- Reduced NOx reduction efficiency (increased emissions)
- Scan tool shows low urea concentration
Severity
High: insufficient reductant quality renders the SCR system ineffective, causing NOx emission limit exceedances; regulations mandate power reduction or engine shutdown if not resolved.
What to do
- Drain the AdBlue tank completely and refill with ISO 22241-compliant product (32.5% urea)
- Inspect the tank for contamination (fuel smell, abnormal colour)
- Check the reductant quality/concentration sensor with a scan tool
- Clear DTCs and verify the code does not return after refilling with certified AdBlue
- Replace the quality sensor if the product is compliant but the code persists