Code result
P206B
Reductant Quality Sensor Circuit Range/Performance
Moderate severity
What it means
DEF quality sensor reads in range but reports an off-spec urea concentration — typically diluted DEF or non-DEF fluid in the tank.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
DEF diluted with water
highOne of the most commonly reported causes for this code — check this first.
Wrong fluid in DEF tank
mediumA plausible cause — test and verify before replacing parts.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Related help
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