P207F — Reductant Quality Performance
The ECU has concluded that the AdBlue/DEF in the tank does not meet specification. Diagnosed by comparing expected NOx reduction against the dosed reductant volume — too much dosing for too little NOx drop indicates diluted or wrong fluid.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Adblue tank
- Nox sensor
- Scr catalyst
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- AdBlue diluted with water or wrong fluid filled
- NOx sensor drift gives false reductant-quality verdict
Possible symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.