P207F

What the Code Means

Code P207F indicates that the quality of the AdBlue fluid (urea solution) does not meet the required standard. The concentration sensor in the SCR system measures the urea content of the solution. If the concentration falls outside the allowable range (typically 32.5% ±1.5%), the DME sets this code. Causes can include use of non-certified fluid, dilution with water, or a faulty sensor.

Symptoms

• AdBlue warning light comes on
• Reduced engine power
• Limp mode
• Display message: “Check AdBlue”

Diagnosis and Repair

Step 1: Check AdBlue Concentration

• Use a refractometer to measure the urea concentration in the tank.
• Spec: 32.5% ±1.5%.

Step 2: Replace the Fluid

• If the concentration is out of spec, drain the old fluid.
• Refill with certified AdBlue that meets ISO 22241.

Step 3: Check the Concentration Sensor

• If the concentration is within spec but the code persists, the sensor may be faulty.
• Replace the AdBlue concentration sensor.

Step 4: Check for Contamination

• Inspect the system for foreign fluids (for example, water or an incorrect solution).

Step 5: Clear Codes and Adapt

• After the repair, clear the fault codes with diagnostic equipment (ISTA/INPA).
• Run the SCR system adaptation if required.

Secondary Damage

Ignoring the fault can lead to the following:

• Damage to the SCR catalytic converter from incorrect reagent concentration.
• Clogging of the AdBlue injector with urea crystals.
• Failure of the AdBlue supply pump.
• Crystallization can block the lines, requiring costly repair of the entire system.

Replacing the fluid and diagnosing on time helps avoid serious expense.