Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 when outside...

Bulletin number

LI49.20-N-078838

Component

Fuel/propulsion system

Summary

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 when outside temperatures are below 32 degrees Fahrenheit. SCR Gen4 (KP7) Complaint: The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes rela- ted to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause: A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to prema- ture freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor to misread levels. D. The AdBlue level sensor is damaged.

Owners of these vehicles have filed 22 complaints in the fuel system category.